The story is that if you want to run for an SCTA record in a motorcycle class you need a motorcycle engine.
Gasoline or "any approved liquid fuel".
Feel free to do anything else, just don't plan on running for an SCTA record.
Yeah, that's the rub, isn't it... but I'd like to have a shot at a record, if I build it, trailer it, and ride it. To my way of thinking, if it isn't at least a contender in its class, it's a waste of time. But if it can't run in any class, that takes some of the fun out of it (at least for me).