Just got a 1970 fastback delivered from NC - fairly solid car - but will need some work to get it where I want. Have a question of gas. The previous owner had it only a year - said the engine was rebuilt before he got it (sure does not look like it) - but put a gas additive in it and ran 93 octane. Is there any way to tell if it was switched over to run on unleaded w/o tearing into the engine. Thanks - I'm sure this one of many questions I'll have once I get into this.

 

It would need to have hard valve seats and the only way I can think of to determine that would be to tear into it. My suggestion is that you continue to run high octane gas and see if it pings. Adding a lead substitute wouldn't hurt either.