What octane should I need?

For street use;
Back off the timing and/or bring it in later. Then sneak up on the tune.
Always buy your fuel from the same pump.
If you have trouble; A) lower the Dcr with a later closing intake point,or B) Delay the secondary tip-in timing, or C) put on a smaller carb., or D) lighten the load/reduce traction, or E) consider water injection.