Allllrighty.... So I got my upper. Went with Blackstone Arms. They had the parts I wanted. But Eric was very very good to deal with. Communications were great. Fast work, super easy. I would have no problem using him again. Polished chamber, squared receiver, GTG.
I got a ARP 16" SOCOM barrel, enhanced bolt, and the Vortex 2 port comp. Went on a Aero receiver and MI 12" keymod guard. I like the MI guard. I like the BCM too, but the MI feels great and has some good features. The upper fit pretty tight on my Mega lower. Just a minor correction and it's a great fit now. Eric offered great service, but no need for that. GTG now.
I'm pretty sure I built a 6.8 and I have a BCM 5.56 to fart around with. :)) Put my PA 1-6 on it. Swap over my BCM ambi handle. Got some AE and Hornady 120 gr SST to try out Sunday. Can't wait to take it out.