I guess you really never know until you try. Wors comes to worst you can sell the transmission and transfer case and just use a 4L80e or buy a 2wd version 6L80E.

Yeah, fuel system will require good quality hoses or tubing. Theres a few guys on here with pre-88 trucks that can help you out with the fuel system for the L92. It probably is a single line, returnless fuel rail. It will be similar to all Fbody conversions if that is true.