[canadian crf]

hi i'm new to this website and there is alot of questions that got awnserd in just looking around and i think this is the best place for me to ask my question i have a 2003 crf 230 i race motocross and watn to get into the 4 stroke division im woundering wat the best motocross frame would be to use i want to swap the motor into another frame so it is more of a motocross bike then a trail bike thx for any suggestions