Just put a vented gas cap on it if you have all the hoses plugged off. The 1970 cars had a vented cap because they didn't have the evap or charcoal canisters.
You should still be able to fill up the gas tank though, even with the hoses plugged off. What exactly do you mean? What prevents the gas from going in the tank?
You should still be able to fill up the gas tank though, even with the hoses plugged off. What exactly do you mean? What prevents the gas from going in the tank?