250-500cc Wanted - WR360 engine

Currently i have the 09 wr300 and to my knowledge its not possible to modify that engine become a 360? if this is the case I am therefore looking for a 360 engine

Please drop me a PM if you have any info on the whereabouts of this mystery engine as I cannot for the life of me find one a 2000ish year model (engine only) :S

My only other option is to sell the husky and buy a used Service Honda CR500.