Any LPK will do they are all the same - I never use the grip or trigger, and buy the bolt catch separately if not included in the lower. Geissele triggers work fantastically, it is all I use. Mostly SSA-E but a couple HI-Speeds and bought a couple SD-E's at the NRA (at a discount insert smiley face here). Bolts and Carriers are very hard to find now. I have been buying stripped DPMS carriers from Midway and a JP bolt wherever I can find them (way too expensive now but I am hooked), I get gas keys, completion kits wherever. Whatever gas block you get make sure it is adjustable. The rest looks good to me.