How Is ignition timing and other tuning options,,,point gap etc. Is carb fully opening when gas pedal on the floor. Are secondary's opening when they should. Are all 8 cylinders pulling their share,,,,no bad plugs or wires, or valves etc. what is a vacuum gauge reading. 3:55's are not really tire shredders if you have a good biting tire. No lead weights in trunk.

Will engine pull rpm above say 5000 rpm.