I ordered the parts to see if I could work on that Raspberry Pi board. I didn't get very far with trying make this work. It would have to be modified as the voltage range needs to be different on a real arcade XY monitor (compared to the one that they used). Figuring out what parts are necessary and what needed to be changed seemed a little beyond my pay grade. I could probably put it together/solder given the right instructions, and program the board, but the modifications are beyond me.
It would make an interesting Rasp Pi setup that could play multiple games on an arcade monitor. It would be MAME, but, until there are alternatives, it might be the only real doable multi-vector option.