Pretty sure I remember for dirt the rage champ spacing of rear is a lot more than a flat kart, not sure about asphalt but I'd contact Jeff at rage and get it from him.
I'd suggest the RR all the way in against the frame (obviously not with wheel or tire rubbing.)
Run both fronts all the way in to the steering arms.
Then work with your left rear for tracking width.
Our Rage stuff is competitive on dirt or pavement, (Jr or Sr) with that starting point.