Convert, but keep running on glow fuel.
Running gasoline requires larger cooling fins. Due to the very high specific power, you would need to run at least 10% oil as well, mainly castor, there are good castor based cart oils around) You need to provide good cooling ducts and baffling/jacketing as well.
BTW,  the crank pin cannot be used for needle roller bearings. The material is too soft at HB30-HB40. Needle bearings need HB60 or more (glass hard, cannot be filed)