Octane additives?

Thank you for that! The seems like a very close comparison? I would venture that I have I bit less compression and if my math serves me correctly your concoction makes about 96 octane? And the 4 to 1 concoction that I proposed is about 95.2 ?
And as 318willwin proposes Maybe a degree or two less timing which I was already thinking about?
If you are going to mix the fuel....... but straight off of pump gas you may need to pull 5* out of timing. That would be trial and error....