All I can add is that when we dynoed my 600-HP 440 at 32, 35 and 38 degrees total, it made the best w/ 35. HOWEVER, the differences across that 6-degree spread were not huge and couldn't be quantified in the manner which you asked.

We also had enough octane in the test fuel (50/50 93-pump and 108 leaded race gas) that more timing than optimal didn't put the engine into detonation. Running on the ragged edge of the engine's octane requirement could have a much different effect when over-timing it.