Earl I would recommend making your own upper receiver. It can be a little more costly then buying a premade one but you get EXACTLY what you want. Research (if you haven't) the different twist rates in the barrels. I highly recommend BCM
www.bravocompanyusa.com they also have a new rail system which is insanely light weight. I have a daniel defense quad rail on mine and I wish I had waiting the 3 months to get the BCM rail cause its so much lighter. I'm currently running a 1/8" twist with a mid length gas system and DD quad rail, BCM BCG, gunfighter ami charging handle. Thing is a tack driver and it's also nice knowing that I did everything on the gun vs buying premades uppers/lowers.
Your spikes lower looks great though! I cheaped out and went with a DPMS for my stripped upper and lower.