Pi2JAMMA with a NBA Jam (4-player) cabinet

[dursly]

Recently I picked up my NBA Jam cabinet, after keeping it in storage for about 15 years. Everything is still working fine running the original NBA Jam JAMMA board, besides a dead CMOS battery and some crackling on the speaker, which seems to decrease once it has warmed up.

Before putting it in storage, I had it running with a PC with an ArcadeVGA, J-Pac and I-Pac. At least I think I used the I-Pac for the player 3 and 4 joysticks and buttons, but I'm not really sure anymore.
Instead of trying to get the old PC setup working again, I want to try a clean/compact setup with the Pi2JAMMA Premium. Does anyone have any experience using the Pi2JAMMA with player 1+2 running via the Rpi GPIO pins and then using an I-Pac 2 to feed player 3+4 signals to the Rpi via USB? Or any other suggestions for feeding player 3+4 signals to the Rpi?

Greets,
Erwin