Ok, so my Pac-Man daughtercard and 6-Pac multi kit showed up today... I installed the daughtercard, hooked it up to the adaptor I made, and plugged in to my JAMMA test machine, waited for the smoke....
And instead, I got a game of Pac-Man!
Which chuffed the ---fudgesicle--- out of me because I had no guarantees the board itself actually worked with the missing parts replaced. Switching the roms back to Pac-man certainly helped.
Feeling bold, I installed the 6 in 1 kit, started up, and got an error message. Inspecting closer, I saw I had accidentally bent a pin- I easily straightened that out, rebooted, & I got perfection. This has been a fantastic day for Pac-Man and family in my household.