I would consult with a mechanic before you go ahead and purchase replacement calipers. The problem might be more to do with another component in your braking system, such as your rotors or brake pads.
If the calipers do need replacing, a mechanic will have to switch them out for you anyway–most of the time, they’ll just order the parts themself and then charge you.
There’s no need to shop around looking at different types of calipers. The ones that come standard in the ZR1 are very high quality, and you know they’ll work properly with your car. Brembo makes excellent top-of-the-line parts. Plus, the monoblock (single-piece) calipers are superior to traditional two-piece calipers in a number of ways.