Nice to see an old game back on the road. See more and more game restores on here for newer ss era games but not as many em ones. Just as you have found the em's may not be super flashy and covered with bash toys and fancy video screens but after a good clean and tune up can be just as fun and sometimes harder.
Grand Prix is a good game. If you get a project one you may hate yourself for getting it been told by many the 4 player Williams games can be a real head banger sometimes but seems you ready for that next em project so i wish you luck.