9.3 looks about right to me too. I am assuming a 600 cfm 4-barrel carb and decent dual plane manifold and headers/mufflers. With the head change alone I would anticipate a 35-50 hp boost. The stock cam is pretty bad. Something in the .510 to .552 range would really help out.

May be able to run 89 octane, probably not 87, and of course once you give it some 93 you probably won't want anything else.

Good luck, Kitz