Mileage translates into wear and tear, and that adds up no matter how well the car was maintained. But the Z was well made, and *WITH PROPER MAINTENANCE* can last a good long time. Check the FAQs on this site.
Look for a car with a well-documented maintenance history. Your best bet it to buy from a rich old codger who could easily afford to care for the car but was afraid to drive it hard. ;-) n