I have 2 PSA uppers. Neither will fit on my dpms pattern receiver from Bushmaster. I do not have a Aero 308 receiver. You can buy an Aero upper and move everything over or buy a PSA lower. I think those are your only 2 options.
Your rifle worked fine till you changed the stock and recoil set up. Underrecoiled is my best guess. Buffer needs to be in the 5oz range. Armalite sells the whole kit. Buffer,tube, and spring for $65.00.
There is 1 more thing I noticed. The gas tube doesn't come into the middle of the cam pin cutout. Armalite has the proper length gas tube. I started with a PA10 as well. A learning experience for sure.