Another update on the 302:
The first one I looked at was shoved in the back of a shed and hard to get a good look at. The second one is on a military storage stand and easier to see. The stand is bolted to a vertical surface on each side of the outer bell housing. The first one I looked at only had the inner part of the housing, so no place to attach rear mounts. At the front, The stand is bolted to the bottom of the brackets that mount the air compressor and generator, so it does have side mounts. The cradle at the front of the engine, that I took for a front mount, looks like the front mount on the 270, but isn't drilled for mounting bolts. It looks like it could be used as a basis for building a front mount, though.
I haven't looked at any of the engines still in trucks recently enough to remember details. We just had more snow, so it may be a month before I can get a good look at them again. For now, I'm assuming that the mounting system in the truck is the same as on the stand.