I run an alt only. I used a BMR alt bracket with a really short belt. Works great.
I also run a th400. Get a TCI LS1 flywheel, and a converter with a snout for a ls1 or you can run any turbo converter with a small adapter ring. Some of the bolts on the bell are not used.
Get a shield or some safety device protecting you from the tranny blowing up. I use a CSR one piece shield on mine.