Compression

In a nut shell the easy answer is; Given the shape of the combustion chamber of the small block Mopar I would stay around the 9.0:1 for regular fuel. You could go to 9.5:1 but the added change in power would be very, very minimal for the possiblity of detonation from variables in fuel quality, air, etc.

I ran 10.5:1 on regular in my Buicks in the early 80's but back then we had lead in the fuel which really helps against detonation.

Chuck