The Raptor 250 is light and nimble, but it's not a mini. You are definitely not too big, in fact you are closer to being too small for it... Maybe someday you will want more power, but you will not physically outgrow it.
The XS650 has always been a favourite chopper engine, but if you must have a bigger motor, then the XS650 can be bored and stroked all the way to over 1000cc. That would solve your problem.