Shit, I'm really sorry guys, I haven't seen this thread in a LONG time.
I've solved this but it take a bit of work and patience. I was 10000% correct about using the Molex KK series headers and connectors. I'd have to get the exact part numbers, but they work EXTREMELY well.
The one caution I will give is that if you're not careful these old playmatic boards seem to want to peal traces as those pins are individual through hole. Its ridiculously stupid as the pins are wedged in so tight. For one of the boards I actually started ripping them up until I got wise: I removed all the solder I could per pin, snipped the ends of the pins on both sides of the board flus with the PCB, and ever so carefully drilled out the remainder with the drill press. It was tedious, but thankfully it was a single board our of the whole pile. After I went back and did some trace repair.
Everything had to go. Every single pin on the board set, and every single wire had to get a new pin crimped and put into the right order. Thankfully the wires had a bit of memory in them, and I went one wire at a time into the connectors. You can also go with a "High Friction" pin from Molex, but honestly that's overkill.
Attached are some pictures of the work as I went. And here's a link to my Flickr gallery of the game... https://flic.kr/s/aHskttPSCb50910036168_5c8f4ef795_o (resized).jpg50910036213_d4239c670e_o (resized).jpg50910036238_0bc22169ef_o (resized).jpg50910036243_28547e47aa_o (resized).jpg50910727776_f283542598_o (resized).jpg50910856297_5b5d80f72f_o (resized).jpg