The easy fix to just make a local driver would be to swap that 4 speed out to a 3 speed of the same vintage. The 3 speed would have 2nd, and 3rd gears synchronized. That would get you back to a stock six bolt axle torque tube if that is the direction you want to go. That unique master cylinder bracket should still fit. Once you start down the other path it will be a money pit in my opinion. If you drop in a v8 well then you will have to upgrade the brakes, then you will have to upgrade the steering, then you will have to upgrade the suspension, then the wiring, interior, 3 point seatbelts, door latches, etc... The list will be long, and possibly never get done. Which would be frustrating.
That 4 speed could be out of a 3/4 ton long bed pickup. I believe they had a 2 piece drive line with a carrier bearing.
Art
