Based in no small part on feedback from my previous questions, I've gotten this far:
Barrel - 16", lightweight profile, mid-length gas system (probably Daniel Defense)
Forearm - free float 9" (model undetermined)
Front sight - iconic traditional front sight base (model undetermined)

Now, my question is, do I need a low-profile gas block?  On the one hand, the forearm will not cover the block, so it shouldn't matter.  On the other hand, the gas tube has to fit under the forearm, so maybe it does matter after all.

It don't matter.  Use a rail height gas block  so you have an easy time finding sights

When you say "iconic traditional front sight base", are you referring to the mil spec triangular type front sight base?
If so, then that is your gas block. You would then go with a 9" FF rail, or a cut out of some sort. Although never seen one for a modular rail.

If you go to a site like Bravo Company and look at all of their upper receiver group configurations, you may get a better idea of what you would like (warning, there are a bunch of them).

With a short forearm, any gas block will work. You may want to consider a longer forearm though. If you are using iron sights, the longer sight radius gives more precise aiming and you have more room for different shooting positions you might want to try.

When you say "iconic traditional front sight base", are you referring to the mil spec triangular type front sight base?
If so, then that is your gas block.

That is what I am talking about, but I have seen some that have an option for low profile gas blocks.  Which is what made me question the need.

That is what I am talking about, but I have seen some that have an option for low profile gas blocks.  Which is what made me question the need.

That option is to swap the front-sight for a low-profile gas block. It allows for you to have longer handguards that pass the gas block or a few other options. But since you want the front sight base, it's not something you should have to worry about.

That option is to swap the front-sight for a low-profile gas block. It allows for you to have longer handguards that pass the gas block or a few other options. But since you want the front sight base, it's not something you should have to worry about.

*click*
Aha!  Suddenly, that makes sense!  I was wondering why in the world.... thanks!!!

I am assuming that you are planning on buying a barrel that has an installed / pinned front sight base already on the barrel, correct?

The only barrel that I know of that comes with a FSB pre installed would be a Daniel Defense.
There are two variations. One is complete, which includes the FSB, gas tube, standard barrel nut, and delta ring.
The second one just comes with the FSB pre drilled, but the pins are left loose.

Usually all others come as a complete URG. Which may be you best bet if you are going to use a standard FSB, unless you have some parts already for your upper build.

You would have more versatility in your upper if you were to go with a lo-pro gas block, and utilizing a longer rail. You can then mount whatever BUIS you want, being folding or fixed.

I am assuming that you are planning on buying a barrel that has an installed / pinned front sight base already on the barrel, correct?

Haven't decided.  The barrel I am leaning towards, Daniel Defense, can come stripped, with gas block only, or with gas block plus front sight base.  Price is going to decide whether I buy the pre-assembled combo or not.  If I can save some $$$ by piecing it out, or if DD insists on also charging me for parts I don't need (like a barrel nut) then I'll just get the stripped barrel.  If the cost is close, then I'll let them save me some labor!

You may be hard pressed to find any DD barrels with a pinned LPGB right at this moment.
They have them either stripped, or with the standard FSB.

I have been looking and waiting for the 14.5" mid length gov't profile barrel(s) with pinned LPGB for quite awhile now.
Everyone that I spoke with said probably not this year.

I finally gave up and went with the Noveske 14.5 CHF middy with pinned LPGB.
Quite a big difference in price points. Worth it, I am not sure yet, but it is available.
They also have the 16".

Haven't decided.  The barrel I am leaning towards, Daniel Defense, can come stripped, with gas block only, or with gas block plus front sight base.  Price is going to decide whether I buy the pre-assembled combo or not.  If I can save some $$$ by piecing it out, or if DD insists on also charging me for parts I don't need (like a barrel nut) then I'll just get the stripped barrel.  If the cost is close, then I'll let them save me some labor!

You don't need to purchase the front sight base, delta ring and the gas tube as an assembly, but if you want a standard A2 style front sight base, I suggest you get it as the option that is already drilled and pins installed.  The stripped barrel will either need a clamp on front sight base set up or you will need to purchase a front sight base with pin holes and have it mated and drilled to the barrel for pining.  Your cheapest option overall is the already installed FSB and barrel from DD, it is also the best option for a standard front sight base set up as it is rugged, reliable, pinned and pre-installed from the manufacturer.  Even if I was going for a low profile gas block set up in order to use a longer rail, I would still opt for the factory installed, pinned front sight base and then I would shave it down and re-finish it.   

Haven't decided.  The barrel I am leaning towards, Daniel Defense, can come stripped, with gas block only, or with gas block plus front sight base.  Price is going to decide whether I buy the pre-assembled combo or not.  If I can save some $$$ by piecing it out, or if DD insists on also charging me for parts I don't need (like a barrel nut) then I'll just get the stripped barrel.  If the cost is close, then I'll let them save me some labor!

IMO you should just get a barrel with the gas block pinned on.  Whether it being low profile or standard A2 style, it's worth the extra costs.  Stripped barrels do not come with the notches required to pin the gas block on.  Which means the barrel will need to be drilled either by you or a smith somewhere.  ADCO does it for $55.  Considering barrels from DD with gas blocks already attached cost $55 more than a stripped barrel, the decision is easy for me.

I don't know where gsmgc got his barrels from, but DD barrels generally do not come with anything aside from the gas block.  You will not be unnecessarily charged for a barrel nut etc.  Stripped barrels only come with a dimple drilled in on the opposite side of the gas port so that you can install a low profile gas block with set screws.

I was just trying to share info regarding the DD barrels. Go on their website, and you can see the different configuration that they offer.

Primary Arms is were I got my complete DD barrel from.

If you are going to send it to ADCO you need to also consider the shipping cost to and fro.

I was considering this at one time http://87ind.com/products/pinblock. Seems pretty good and somewhat easy to do.