We'll see about that.
Still have some SEGA related stuff to check out (Model2/2A/2B/2C) - I happen to own the boards, but need to build an adapter for my ISA interface board. Also there was that Y-Board comm board for powerdrift.
Other stuff may be as simple as a serial connection that needs to be hooked up. (at least the cruis'n games seem to work like that).
everything that has a dedicated network controller with a CPU and ROM will be some journey - and of course someone needs to be kinda dedicated to figure out that stuff anyway

expect linking in powerdrift next, maybe model2 after that... I'd like to try daytona (2), srally (2a), indy500 (2b) and most likely stcc (2c)