To the original question, I think I would stick with a chassis designed for 4 cycle racing. In no particular order, there are a ton out there: Coyote, Razor, Ionic Edge, MGM. I’m sure there are even more. This doesn’t mean you cant be fast in something else, just easier to get support and set-up help for your situation.
That being said, the fastest of the fast (that I have seen) use old Arrow 4S chasses. If you can find one of those, it would be worth its weight in gold. I have also seen people have quite a bit of success on the new Comet Eagle. They are very similar to a 4S and get pretty good support out of Comet Kart Sales.