Except #3, I dont' think the compression is "terrible" for a untouched stock 318. Could be better, around 140 psi across the board. I'd pull the heads, buy new exhaust valves and have the seats touched, then have a valve job done on the intake side. check the guides. Problem i have is the '71 may not have hardened seats. IF that's the case, I wouldn't spend the time or efforts on them. I'd replace them.
