It's a quarter tank each way to the nearest 110 station.

Yes, you can have damaging detonation without actually hearing it, if you are attuned to your engine you will feel it as well. I feel a slight drop in power at quarter throttle or more at a point in the power curve where it should be increasing. That's why I limp my numbers-match engine with backed-off timing until I can come up with a proper engine budget. Pull a spark plug on #1 at TDC and shine a bright LED light in. Use a fiber optic viewer if you have one, otherwise use a mirror or just look for pits on the top of the piston. I have a couple of OHC pistons that look like someone bounced framing nails around on them for a while. With an OHC it's even harder to hear, as the cam tower is on top of the head on top of the block.