Stripped lower (maker doesn't really matter)
Rock River LPK
Whatever A2 stock kit I can get my hands on
Maybe a Magpul MOE pistol grip... prefer those to the A2 type
Bravo Company 20" Upper
BCM Gunfighter charging handle
Rear sight of your choice
Easy enough. It would be a perfectly good rifle and BCM makes darned good barrels- my 16" BCM upper is astonishingly accurate; more so than I am.