67 Mustang - store it or drive it?

Rubber goes bad with time. It doesn’t matter whether its stored or driven.

Rust also occurs with time and if the car isn’t moved occasionally, the oil film will drain off the tops of gears, out of bearings and the top of the engine. Then they rust.

Storing for a few months is not the same thing as storing for 10 years.

I did 20 years in the Navy and had to store cars for 6-8 months at a time, I always came back to problems. On the last car before I retired, the secondary throttle corroded and froze in place. The car was hardly worth driving after that. When my son was in, he left a car in non running condition when he went on a cruise, had to send it to the junkyard.