You shouldn't need high test for where you are and what you have. Timing is important, but timing is not just the "how much", but also the "when". So when the centrifugal starts and finishes is just as important as the amount of advance. You should also focus hard on the step up springs in the carb, and the sizes of the steps on the metering rods once you get the timing curve done. I don't think you'll need super unleaded, never mind the octane booster once the tune is right.