I want to assemble an M16A1 clone, but I'm having trouble finding a couple of components. The only A1 uppers I can find are sold by Fulton Armory ($150 without the rear sight assembly) and Nodak Spud ($180). I'm also having trouble finding a suitable barrel. The only A1 profile barrel I can seem to find is from Green Mountain, but it has a 1:12 twist. Ideally, I'd like a 1:7 twist for shooting heavier bullets.

Any leads would be much appreciated. Thanks.