I saw a ad for a M16 upper w/o the foward asst. is it legal to have a M16 upper on a post ban? If not, are there any companys that make post ban uppers w/out a foward asst.? I was thinking about a Vietnam era project, 16" barrel with a fake flash suppersor, no foward asst. upper, and a pinned collapsible stock.

Your vision is completely legal, the actual upper receiver doesn't matter, only the barrel configuration (no bayonet mount, flash suppressor).

You could just buy an SP1 upper. They come without the forward assist. I just bought one recently with the 20" length barrel for my vietnam version. I also purchased a early A1 butt stock without the trap door to go on it. I'm going to have Jayson at IGF put on a Wilson Combat muzzle brake and do the conversion for me. He charges $130 plus $18 for shipping to do the conversion and refinish your complete rifle.

Sarge