I ran a 400 hp 350 on the street in the 80's with 11.5:1 CR. Ran unleaded premium. At first it pinged a little, then I indexed the spark plugs so that the gap pointed up between or towards the intake valve, and the pinging stopped completely. I ran a Mallory Unilite back then with a 40 kV coil; point being you'll want a good spark ignition IMO.

An alternative to race gas is a water injector. I did the race gas bit with my 68 427 Vette running 11.7:1 CR. IMO this would be less of a PITA.

You might consider some aftermarket aluminum heads as well.

Regards, Kitz