It's good to know that you came up with the same results I posted here a couple of years ago, testing with a similar engine configuration and with the same brand of lead supplement. The biggest difference is that my 'bird responds best with a 50-50 mix of 110 and 93, rather than a 12-5 mix.

Fuel brand selection is still important; my 'bird does not like the fuel available from the local Mobil station but runs fine on BP. It's easiest to feel fuel differences in low speed driving with no added octane and no lead additive, with only a couple of gallons added to an empty tank.