I'm an Insurance Agent... RX7 will be somewhat lower. The liability will cost a fortune on the z28, but undoubtedly has a lower symbol rating (my 96 z28 was a symbol 16 through my company if i recall correctly) ... just stick with RX7 for now unless you're prepared to spend up.

just get something you don't have to carry full coverage on and carry state minimum limits 25/50/25 with matching Uninsured Motorists coverage limits until you turn 21.

then go get a LS1-powered car