If it is truly that short of a distance, you may want to really consider moving the rear back to gain as much room as possible. A short driveshaft works on some very odd angles and the u joints can bottom out against itself on up and down movement. You figure, by the time you get a tranny yoke in there and a rear yoke, your shaft will effectively be like 6 inches long.

Just a suggestion, but I would slip the engine and tranny back in and measure for sure. That extra long pumpkin on the 8 3/4 rear really chews up some valuable space.

Don