Get a 1969. Make sure the heat works if you live somewhere that needs it. Change the oil and adjust the valves every 3000 miles. Set the valves a touch loose on #3. Lube the throttle and clutch and heater cables in the tubes. Watch for rust on suspension parts. Make sure the floor pan is solid and keep it that way. Keep the plastic cover over the positive battery terminal. Keep the fuel line away from the throttle linkage at the engine. After that, it's just normal maintenance. I don't care HOW rare they are, avoid the auto-stick shift transmission models. Some parts are nearly impossible to find for them.