Use felpro #1003 .041" gasket to tame the motors cr for use with pump gas.
Your cr will be 10.72:1. Use non -projected tip sparkplugs with a heat range slightly cooler than stock 3 to 4 heat range levels. Go easy on ignition advance 32 to 34deg should do it. give it a good bit of initial advance at idle but limit and fine tune the vacuum advance rate and amount.
May have to up the carb jetting a few sizes to keep 'er cool. being slightly rich helps.
If that fails you'll have to remove the heads and relieve the chambers to lower the cr. Opening up the chamber to 65cc using the same gasket gets you 10:1 even. you'll gain some flow and power to boot.
Gap your plugs at .035". Make sure the ground strap does not go past the center pin. Trim back the ground strap length if nessessary.
A water/methanol injection system would be nice.