It doesn't look TOO bad in terms of a Bally/Stern corrosion repair, but definitely looks ugly with the wires running everywhere. With it already booting, you're way ahead of the game. You'd likely have to re-add at least some of the jumper wires after removing the corrosion because some traces will be toast after sanding. You could do a nicer job of it though
You might get away with no jumper wires using a DS1811 reset. That's by far the best option, in any case. The damage looks to be mostly in the reset circuit.
Just noticed how they modified the reset. Haha! Nice work, actually.