While I do not have the direct answer you're liking for, I will recommend that some more info would be helpful for whoever has done the replacement. What are you trying to accomplish with the replacement? In other words, are you racing? Do you run mainly on or off road? What type of terrain is typical for you? Are you looking for top end or stump pulling power? Etc.... More info will be helpful and will likely help to get you an engine that will make you happy! Good luck and plz post some video when you get it done!!!
A well tuned, well Maintained, broken in right 3.3 will be plenty of power for any beginner. They're not a bad engine as long as they're maintained and broken in right.. an upgrade would be a picco max .21 or os21tm.. those would be my 2 choices