i can highly recommend John Thomas at Retro Arms Works, Warsaw, IL.
if you're only sending it out for pin & weld, and nothing else, the round-trip shipping will be "discouraging", part of the cost-of-living in Hawaii. However you package it up to send it out, that's what he uses to return it, so if you pack it crappy, that's what you'll get back.
I usually send him my projects for pinning the A2 FSB to the barrel, pin & weld muzzle devices, things like that.
you start off by sending him an email for a price quote, jntmjt1@yahoo.com.
his work quality is top notch, and turn-around time is typically 1-2 days. read up about him on arfcom.
I used to send my stuff to Randall at AR15barrels.com, but his turn-around time varied from 2 weeks to 2 months, quality work, though. had a few barrels shortened, threaded, pinned & welded MD. Even some 1/2-36 for 9mm PCC.