Brewer's swap vs Sourcing Parts

I think I have access to a b-body a833 that has been rebuilt for $1000. Could negotiate probably.

Is there a guide to the necessary parts somewhere?

No on the B body trans. It mounts the shifter in the wrong spot and the tail is longer so the drive shaft wont work without being cut. As far as doing a conversion I have done it be patient and you can do it for 1/2 cost or less. If you have a 904 now your drive shaft will work and the other parts can be sourced from Ebay as I have done but some parts you will buy new from Brewers.