Seems Repairable. I would give it a try if you were in Europe.

You can do it yourself step-by-step every day.
I'd start by firing it up and see what kind of problems I have in my machine.
Then I'd make a list of tools & supplies I will need (readable schematics, dmm, clamps/aligator clips, soldering/desoldering station, metal contact brush, IC tester, IC sockets, fiberglass pen, sandpapers, green epoxy pcb paste, etc etc etc)

You must also determine what caused this corrosion. Seems like alkaline vapours from battery leaking got different areas of your board. If so, I would neutralize with white vinegar first (you'll see bubbles forming from the reaction if it's alkaline)

Lastly, be careful with the temperatures you use on your PCB, as these old MPUs can flake and lift traces if you leave your soldering iron touching for too long.