I think a minisprint guy I know was thinking of doing the same thing with a 600 motorcycle engine and installing in a midget but they wouldnt approve. Maybe email Tony at Rumbleseries@aol.com to confirm so you will have a early jump on next year. He is usually quick to respond.They let me bring in a Quad 4 this year but I got prior approval and I guess they had ran in the past.
Just a thought.

Chris