Also, this thing has an output-PLA similar to TMS1x series. I've read about someone(nickname: blanka) that decapped a Frogger MCU. Is the die picture online somewhere? And if so: more than just the ROM.
A couple of shots of different parts of the chip with an inexpensive microscope... I don't think he has the chip anymore, so we'd have to sacrifice another one to get better pics... But maybe this covers what you need (assuming they are clear enough)?