I was lucky enough to get some stick time in a Zlin 242 at Stewart w/ a very good instructor (won 1/2 hour free lesson at an airshow raffle)... couldn't do any spins because of haze, but we did some loops and rolls. It is demanding physically, so you may be uncomfortable at first. But as Hagar points out, once you get the stick, it's a whole 'nother deal!! Suddenly I didn't mind pulling 3-4 gs at the bottom of a loop!! Did pretty well, too... Holy crap- to be upside-down in an airplane...!! Yippee!! And while the Zlin isn't as hot as a Pitts, it was a thrill just to have my hand on 300 horses in a plane that weighs about the same as a Cessna! You're gonna love that part of it...
We landed and I decided to pay for another 1/2 hour. We went back up, and he showed me some rudder-coordination exercises and unusual-attitude recovery stuff that would work in a 172 or similar non-aerobatic bird. Fun!!!!! And useful...
A little advice: don't do what I did, which is have a light breakfast. I noticed Saratoga's post, but ...According to my aerobatic CFI, you're better off with some ballast in there ( " I always have a big ol' greasy breakfast before I go flying!"). But be prepared for that odd feeling when you're "pulling gee": feels like your guts are being shoved down into your pelvis. And if you drink coffee, take it easy that morning- caffeine doesn't help with the nausea, either. And being a smoker didn't help me, so if you're dumb enough to smoke (as I do), then beware. The diminished 02 in the blood will not help matters. If you don't work out and there's time, I'd even advise a little light exercise every day before you start the lessons, to bolster yourself a little. But i'm no expert- ask your instructor about all that.
I received all that advice when the CFI noticed I was getting a little green and sweaty at the bottom of each loop ("let me guess", he said after we landed, "you're a smoker, you drink coffee, and you purposely had a light breakfast..."); didn't barf or anything. But if I had, I would have been smiling while I did so...

Don't let anything I've said here put you off: just trying to help you prepare. As a pilot, you're gonna have a ball!! And if time permits, ask him if there's anything he can show you to help you be safer in the 180. Even if you just horse around, though, you'll come away feeling more secure in your knowledge of what flying is all about.
Enjoy!!!