Is there are reason you're not willing to remove the A2 front sight and replace it with a low profile gas block?
If it's because you have a pinned & welded muzzle device, that's not very complicated to remove with the right tools without damaging anything.
My first "build" was a stripped lower and complete upper from PSA. I went that route mainly because i wasn't sure what i really wanted in my 2nd AR after the Colt LE6940.
What i decided was I wanted a free floated barrel similar to my Colt. The most direct solution was to replace the handguard and gas block/A2 sight post. Since the barrel was 16" without the flash hider, I had no problem removing it. i had already purchased a replacement for it anyway -- something more effective at hiding the flash than the birdcage design.
With a little research, i knew what diameter gas block I needed, what tools I had to buy, and what handguard i thought looked promising. I also purchased a front sight to attach to the rail. The number of parts was minimal, and the handguard was the only big ticket item -- I think i spent less for my Troy handguard than the one you have now.
I did all the work myself, and even chose the same configuration for my next build -- which was actually for my daughter. She liked the look and feel of my handguard, so that's what we chose.
Anyway, unless you have a need for the A2 sight post, i'd say ditch it. Colt offered free floated barrels with A2 posts, but i'm not sure i've ever seen any other company offer them. if a barrel is free floated, the handguard is usually over the gas block, and the front sight is on top of the handguard.
One of the benefits of a flip-up front sight, besides the obvious, is the longer sight radius. The more distance between the BUIS, the better your sight picture.
Of course, the A2 can hinder the use of many optics as well. Another reason to consider ditching it. Flip-up sights are only visible when they are needed and out of the picture when they aren't. Even if the sights are 1/3rd co-witnessed, I found having the front sight anywhere in the viewing area of my optic a distraction at the very least.