Help me pick my tire size

I'm looking to finalize the wheel/tire package for my 95 Miata. It's got the Flyin Miata Vmaxx Xxtreme Sport Pack treatment on it and if I had to guess it will see about 3,000 street miles, 15-20 local autocrosses (STR class), and 1-2 HPDEs this year. Right now I'm really liking the 15X8 wheels from the Flyin' Miata Targa package (http://www.flyinmiata.com/wheels/index.php). I'm pretty sure I want to go with Rivals (I had Star Specs on stock rims last year), but I'm not sure what size to go with. It's 205-50R15 vs. 225-45R15. From talking with the guys at Flyin' Miata it sounds like the 205s will definitely fit without a problem. They also said that the 225s will "probably" fit fine, with a small chance of rubbing. So I have some questions from the GRM collective:

1. Lot's of you have Miatas; any thoughts on fitment issues with 205 or 225 tires on an 8-inch rim on an NA Miata without rolled fenders?
2. What are the performance pros and cons of the 205 vs the 225? They are pretty much the same weight and are also very close in price. The GRM track tire test indicated that both sizes would run the same speed on an 8 inch rim. Would that hold true for AutoX as well?
3. Not really a question, but feel free to try and talk me into something else...the enormous Miata aftermarket is tough for me to navigate sometimes and maybe I've missed the best option of all.

1) I have an NA with slightly rolled fenders and +36 15x9/225. No tire rubbing issues.

2) Tough call, but I would imagine the performance is extremely close on the 8" wheel.

At this point, the answer is to go with the better compound.

225 will likely require a roll. The 225 will be fastest on a 9" wheel. The 205 will be fastest on an 8" wheel. Doubt you'd see much speed increase going to a 225 on an 8" from sizing alone, but if you have a better compound in the 225.....

i found this site and its a bit more in depth than youre asking for but still a nice calc.

http://www.cargister.com/calculator-gear-ratio