Thank you for all the advice, guys.
When I fill premium at the pump I have in fact been running a couple gallons into the tow vehicle before filling the fuel jugs.

I talked to the fella who built my engine and he believes it to have about 10.5:1 compression, with aluminum heads. The best pump gas I can find where I'm at is 91 octane.

So dang much snow yet where I'm at in SE South Dakota that racing is being postponed.
T.