Help! C6 Z06 Replica wheels/tires on a C5???

[LegendRacer]

I need some help on this one... have a 99 with the stock wagon wheels and I am looking to upgrade them. Found a killer set of used replica C6 Z06 rims/tires but they are different sizes than the stock C5 rims. I am not sure if they will fit, might need a wheel spacer. Here are the dimensions:

Stock
Front 245/45zr17 on 17x8.5 rim
Rear 275/40zr18 on 18x9.5 rim

Upgrade
Front 275/35zr18 on 18x9 rim
Rear 295/35zr19 on 19x10 rim

Any help would be greatly appreciated. Also concerned about speedo... THANKS!!!

LegendRacer