There seem to be 2 different variants of the M37450 in use. One is a stock Mitsubishi part with no internal ROM used on finalap3jc (at least, if not other games) as seen in this picture: http://smitdogg.mameworld.info/pics/final-lap-3-j-1.jpg (it appears as though the chip marked sys2c68 is dumped but not yet hooked up in namcos2.cpp)
And the second is the Namco C68 with undumped internal ROM (last I heard one was sent for decapping but I dont know what happened to it or whether its still in the decapping queue)
Other boards with the c68 have external program ROMs (the driver mentions some of the sws sets for example)
If anyone has any further information (e.g. whether the internal ROM of the Namco C68 has been dumped or is in the queue to be dumped or whether wiring up Suzuka 8 Hours and Suzuka 8 Hours 2 with the correct C68 internal program with no external ROM rather than whatever MCU program they are currently using will make any difference to the controls of those 2 games) please feel free to share
EDIT: I also found this other picture: http://i.ebayimg.com/images/g/G9oAAOSwCU1Yz8BR/s-l1600.jpg of a Suzuka 8 Hours 2 PCB which seems to be clear enough to read the "C68" designation on the MCU (as opposed to the Mitsubishi designation in the Final Lap PCB picture)