Well I have been looking up on this a bit online and mainly what I have found is the following:
1. T350 crossmember can be used, but needs to be moved an inch or 2 (requires drilling new holes in frame
2. Driveshaft shortened (which is cheap at the local machine shop)
3. I saw a couple things about installing the lockup kit? And some vacuum lines?

Currently in the el camino my t350 doesnt drop into passing gear except manually. Which I think is because of vacuum but I am not sure.