Hold on now. If your pistol is from 1993 (and possibly older than that, knowing CZ's habit of dating older stock with newer serials and date codes), then it falls into the mysterious "transitional" period. Basically, this was the time when CZ was phasing out the original CZ75/85 in favor of the new 75B/85B, and to do that, they needed to work their way through a large inventory of old stock, mixing and matching new/old parts as they went along. The big difference was the inclusion of a firing pin block safety device (the "B"), and you can immediately ID your's as having one by looking for a small hole in your slide serration area. The presence of older-style text will also ID it as an older gun, but not always, since transitionals are weird like that.
Older frames were slightly smaller, so modern-day mags will NOT work in older frames. You might have to search out the increasingly rare old style mags, which, I'm afraid, can be a real hassle. Older 75/85s are also slighlt different internally, so some modern day replacement parts won't work (safety and ambi slide stop, for example).
As far as replacing the recoil spring, you may not need to, since 5-600 rounds isn't all that much. If you want to, though, you can use a 75 spring just fine.
Do you happen to know if its a Combat model? Early 85 Combats didn't have any special markings, and were only identified as such with early-style adjustable rear sights and the modern-day squared triggerguard. I mention this because if you want to properly ID this as an older frame or not, the Combat's squared triggerguard will make it a bit more difficult.
Any chance you could post some pics? We might be able to help you out further. Plus, its never a bad thing to see another CZ out there! If you can, show some pics of the mags- that'll be a big help as well.
