Advice on rear swap

Thanks for taking the time to give your opinion here.

I want to get rid of the 7 1/4 next year when I swap my slant for a 360. Mild street car.

I want to keep my SBP Cragars since I have new tires on and just did a disc brake conversion to keep the SBP on the front. (Scarebird)

A local seller has two rear options I can buy for a pretty good deal.

1. 8 1/4 out of a Duster. $150
- I think I can just get the drums and axles machined for the SBP right? Should be good to run after that. No need to modify spring perches.

2. 8 3/4 from an E Body. and he has SBP Axles to sell too. $100
- I would need to find someone and pay to get the housing shortened and also have the perches moved.

Trying to go the cheapest route here. Has anyone made an 8 1/4 drilled to SBP before?