265-35-18 and 215-40-17.
I really know very little about tires and the web is confusing. I searched everything from tire rack to costco. I want tires that are maximum summer perfomance with reasonable wear.
I don't track but since Sebring is only 60 miles away, It's not out of the question. So Dunlop Z1's. 2's? Faulken, Michelin? Yoko?
Those are good sizes to use on your '93. And if you've never tracked, it's not a consideration, even if you want to try doing your first couple of events with whatever you get.
The big question is whether you're willing to trade off a little more grip for a little more treadlife. For the most grip, you'll want one of the "extreme performance summer tires". These are available in those sizes:
Dunlop Direzza Sport Z1 Star Spec (being discontinued)
Dunlop Direzza ZII (its replacement)
Yokohama ADVAN Neova AD08
Falken Azenis RT-615K
All of these are very good, and you can't go wrong with any of them. (I'm eager to hear more about the new ZII, and if it's truly better than the Star Spec, that's a real accomplishment! But note that they won't be in stock at Tire Rack for another month, in either size, so if you need them right away, they're not a candidate.)
For somewhat better treadlife, and somewhat less grip, you could get:
Kumho Ecsta LE Sport
Personally, for a highly-modified car like yours, I'd go for the stickiest tires I could get rather than worry about treadlife - after all, why do the powertrain mods if you're not going to get the tires best able to put the power to the ground - but that's the trade-off, it's up to you to decide which way to go.