Run the lowest octane you can without pinging. You don't say if you have factory or higher compression pistons. Pistons with a factory size dish will run fine on regular grade fuel. When you get up to around 9:1, you might need a mid grade, depending on timing and advance. 10:1 would probably need premium, anything higher than 10.5 may need race fuel.
Cam will determine the dynamic compression ratio, which will play a bigger part than static compression. Someone here had a calculator.
See this thread for more info:
http://www.bulltear.com/forums/viewtopic.php?t=6142&highlight=fuel
Bob
tufcj
