I know its not AC, but In 1995 I was offered a burnt Minneapolis-moline ZB if I could haul it away. The tractor had burnt in a barn fire in 1962.
The block (and cast pistons) were still real close to original specs, so I re-used them in the rebuilt engine. I could have used the crankcase as well, if I had been energetic enough to clean it. It still had oil in it but had been hot enough that the babbitt flowed out of the bearings.