If I were the local law enforcement I would have been all over that stuff when it was first uncovered after all these years and I would be checking the vin #s on all the engines,trans etc. and check them against old vehicle theft records to see if anything raises a red flag. Yes,maybe some big blocks were replaced for small blocks during the gas crunch but what about all those complete small blocks with the exhaust manifolds still attached that are there and the trans. with the shifters still attached to them. Maybe the trailers were welded shut and he didn't talk to anyone about his stash for a reason.It looks more like remnants of a 60's-70's chop shop. But the cars seem to have been purchased legally.
Just a thought.