I am putting a 6.2 HMMWV motor in my GMC in a few weeks. Just waiting for it to arrive. The truck is similar to the M35 series in that it uses an air compressor (big 2 cylinder) to make air power for the AIR PAK. I already fabbed up a mount to fit the same compressor to the 455 olds that used to be in the truck. It came out okay, was solid, had it belted, made a tensioner and everything. Never did get to try it out though since I decided to sell the motor. Found pitting in the cylinders and I didn't feel like driving around on a POS motor.
Sooner or later all of us car/truck guys face the task of putting something onto a motor that wasn't designed for it. Be it a compressor, alternator, power steering pump, whatever. If you can weld good and cut steel, you can do it. It just takes lots of patience and lots of brainstorming. After you've made your first successful mount you'll feel like you can do anything. No longer do you worry about finding bolt on crap, if you need it you just make it yourself. Plain and simple.
I will take pictures when I get the compressor mount made again. I can explain how I made it as well. Measurements if people want, too. I like to utilize off the shelf flat stock, tubing, etc.