any input

Don't mess with the Doba rear. It's probably a 9 1/4, grab the drums and backing plates off of it if they are cheap.

If you are going to swap the front to big bolt pattern disc, grab a 66-70 B body rear. They fit and the only thing you really need to do is spread the springs 1/2" on each side and you get the BBP drum/axles. You'll need new wheels as well so buy the correct offset to make up for the wider rear when purchasing.

Your car is already a floor shift manual according to the tag. You'll need a new bellhousing because the /6 one won't work, flywheel, clutch, shifter and trans. The z bar will need to be shortened, /6 is wider than a v8 bar.

I wonder if the 5 speed is an A833 4 speed overdrive trans. It's a good trans as long as you don't beat the living daylights out of it. Alum OD trans shouldn't cost more than $100.

Nice Nova Dude!!! :-D
You'll hear that one every once in a while.

Good luck. Love the 70-72 Dusters.