A few pics finally. Here's the D300 case with the clocking ring on it:
These show the modification to the 1980 version D300 to bolt on a "normal" HD output housing designed for a 1981+ 'case:
The 4" stretch, and cutting a 37" diameter wheelwell. I cut nothing from the front of the wheelwell, and about 1.5" or 2" off the rear. The scribed line just over the cut is the actual fender line, I have a piece of 1/4" rod rolled to the same diameter I'll weld to the inside of the fender, then hammer the sheet around it so it has a finished, reinforced edge.
Here's my engine and tranny:
The engine block side of the motor mounts were built to accept this bushing: