Hi All,
So I decided to take a stab at swapping the MPU myself. I started by attempting to remove IC5 from the replacement board.
It was a total failure

That thing is microscopic. My main problem is / was that it's impossible to heat all the legs at the same time, so I can really only release one or two legs at a time, which is really not helpful at all. It was good practice, but I think it would take a lot more practice before I would be able to do that chip swap myself.
I suppose there's a slim chance I could get the chip to release using something like "Chip Quick" or whatever it's called that stays molten longer. Even that though, I would say is a real slim possibility.
Over in the HW forum, someone else has offered up a donor drive that looks like it's got all the proper matches on numbers, including the MC62 on IC5. I guess I'll give that a go and see where it lands me.
Thanks!
Chris