Outrun 2 - too much hassle to hack. Would probably need a custom arduino interface. I don't know if anyone's done it yet.
I'm assuming the NFS cabinet only has an up/down shifter and uses a separate nitric board for the pedals. If so, it's out. (the fact that it already uses the immersion pcb and PC compatible monitor might put it back in the running though)
Rush the Rock and Rush 2049.
Both use Happ setups that would be compatible with an immersion board, but you'd have to make your own wiring harness.
If both have 4 speed shifters it would come down to which monitor is easier to interface with a PC or which one has more buttons on the CP.
I'd want the 4 speed for the sega games, but if more modern PC games are important, the Up/Down sequential shifter will work better with those.
That's my quick opinion anyway.
EDIT: Some discussion of the Nytric board in the NFS here, but it doesn't sound like anyone came to a solution:
http://forum.arcadecontrols.com/index.php/topic,152492.msg1596562.html#msg1596562