So I was thinking maybe you could take the ethanol out of the fuel and add some of this to it to boost the octane back up:
https://www.murraymotorsport.com/vp-racing-fuels-octanium-unleaded-fuel-madditive---0-95l-vpr29505?currency=EUR&incl_vat=1&gclid=Cj0KCQjw-pCVBhCFARIsAGMxhAea1oV7TkNs1q0PJuK6qmkE33LSjw8U_yO9zBrQQmBWa32l8XNUa3IaAoneEALw_wcB

or if you have an infinite bank account just run this: https://www.murraymotorsport.com/motorsport-109-ms109-unleaded-race-fuel