[rotorwrench]

The Bishop/Tardel book has some photos where you can kind of see how they went through the edge of the recess so the spoon would be inside with the bearing blocks attached to the engine side of the recess along with most of the shaft. Only the spoon and a bit of the shaft protrude into the cabin side.

My AV8 project is at the stage where I have the parts but with other irons in the fire, I haven't gotten to the mock up stage yet. I'd suggest getting your engine, transmission, and radiator locations solidified then start fitting pieces to get a good location, shaft length, and configuration. Too many variables to do otherwise. There were several configurations of spoon & jackshaft arrangements in the 30s & 40s. Some work well and some are either too long or too short.