Why both sets of wheels? Not sure I follow the logic of the 8" wheels unless you wanted to run a 225 tire. I've tested both and the 205 is definitely faster than the 225. Even when running the 8" wheels. And besides, the 225 tire on the 8" wheels running a competitive spring rate for Autocross at the ride height you needs for Autocross rub in the rear under full compression; unless you go with some aggressive fender rolling/trimming) With the 7.5" wheels, 205 tire and 5mm spacer, all good. In the front the 8" wheels rub the strut housings with too much negative camber (over -2.5) if you adjust it through the strut bolts. With camber plated coilovers, this is a non issue. When you go full steering lock, they do rub the inner fender liner on the rear right near where the accessory mud flap (wheel splash guards) would mount. Not an issue on the track or course, but as a daily driven combination, this could make parking annoying.
If you want the 8" wheels for the increased track width, just get a set of extended studs and run the 7.5" wheels with a 5mm spacer and the 205 tire. This is the "sweet spot" between width, track and lightness also..
Best of ALL worlds...
But if you already have the 8" wheels, or have another car that the 8" wheels fit and you are going to move them from car to car depending on your fancy for that track day (Zach), then go for it.. But if the 2 IS your track car (HPDE or Autocross and daily driver), I think you'll be happier with the 7.5" 205 tire and spacers and have a bit of extra cash (from not having 2 sets of wheels and tires) to spend on a couple more event days.
Unless the SMF/SP bug bit you, poisoned you and ruined your logic; then be prepared to dig a hole in the asphalt, toss huge amounts of cash in weekly and set it all on fire...At least that's what it felt like in my SM/FSP days...
That being said a forced induction 2 with all the added lightness tricks, massive 275/45 Hoosiers cut and widened fenders and crazy stupid spring rates to keep the tall beast in check WOULD be an awesome sight....I look forward to seeing it if you build it...