Keep your car and buy the S30!
Does your car have A/C? Does the Z have A/C? If your car has A/C and the Z doesn't be prepared for a shock. Z's to me are not cool temp wise inside and plus your in Texas. Then there is the fume issue and women do not like exhaust fumes, at least mine doesn't.
The other thing to consider is maintenance. It something goes wrong with the RB your ordering parts. Not that the RB is not reliable, but you can't predict the future. The Chevy you can go anywhere.
Definitely find out how long it has been painted. If it was recent, see if he has pics showing before. These cars are notorious for rust.
Try and make your decision on facts, not emotions. If you have the cash to buy it outright go for it.