340 build advice needed

I suggested what I did due to a previous engine I had. A 9.8-1 ratio 360 w/J Heads, 2.02's and a purple 292/.509 cam. It did run on 93 octane. But nothing less. A bad batch of gas and I was screwed.

Ignition timing has to be spot on and fuel quality good at all times. Your cam is smaller which builds more compression which needs just exactly what I said. IMO, I would look for that thicker head gasket for a 10-1 ratio. Or slightly less.

My being super close to sea level may have mena but nervous for you so if there is an error, it is in the side of caution.