Another very effective octane booster is MMT (methylcyclopentadienyl manganese tricarbonyl)
used in Bardhal Instead O lead Gold, which I think you can still get and works excellent.
I used to have a old Buick that liked octane. It was OK around town, but if you hit the highway it would rattle bad at high speeds. I kept this in the trunk, one bottle in even a full tank of 26 gallons stopped all the pinging. Good stuff.