/6 questions

Talk to Advance Adapters and Novak. I found a dead link so I couldnt get the details but someone was able to make an adapter out of a piece of aluminum plate and maybe an input spacer ring to bolt an AX 15/NV 3550 behind a slant six bell housing. Novak has info how to do it behind older Jeep engines. At your weight, I would want a GM NV3500 due to its larger output and redesigned (stronger) internals but the cast in gm bellhousing is a potential dealbreaker, unless someone makes a manual transmission adapter. If the starter mounts to the bolt housing, a fabrication shop could cut an adapter plate. Then you also have to have a spacer for the flywheel and use longer bolts, but studs and nuts are a better option if there is enough room in the bolt register on the flywheel.