I haven't personally driven a ZR1, but the "main" difference is that the ZR1 doesn't have an overdrive, it's all pull, all the time. 1-4th are very similar, but 5 & 6 still keep pulling strong. Would probably suit your car really nice. I think it's a crap ton more expensive than a ZO6 unit though. You'd probably be better off just getting the sequential gear box from LG motorsports over the ZR1. Now THAT'S a transmission.
Good luck, at least you KNOW your car is in good hands now.