A local who races a Alltrac was faced with the same decision after the end of last year, I think he melted the pistons on the stock one. After looking are factory rebuilds he found a stroker kit that pushed the motor out to 2.3L or something? (sorry not real familiar with them). He said for the price it was almost the same as rebuilding it stock, but now it makes more power and has better internals. Sort of a homebuilt effort so its not pretty, but its fast as hell and has won SM a few times against EVO’s and Subys.