Did you see the one 4 sale on CL for $999? He might have a harness too but don't really know except that he had a lot of parts.
I have a 1985 with around 130k on it that was running very good except for some smoke due to the need for new valve seals.I do not have a harness though. I am looking to get $600 for the motor with ECU picked up in San Diego.
Why not just buy any year 5M and transfer all the unique parts from 82 over from your original motor? That opens your field up to like 88 Cressidas. You should also look on car-part.com since some wrecking yards still list these cars.