Hope I'm not derailing this too much. But I got my Namco board working.

Hacked a ATX 20 pin connector to power the board, it fits perfectly. Then used a JST HX connector for RC lipo batteries for the RGBS and ground. Turns out my CRT has S-Video, so wired that and voila, everything worked as advertised! I was worried the middle pin on the power connector is for 5V, but looks like it has onboard regulator, not sure what the middle pin does.
@Franco23444 do you have a manual or have you figured out what all the other pins were for? Like 2 behind the S-Video connector and the trimmer pot to the right of it. Not important, just curious what else this board could do.