I think 450R shocks are too short, Don't know about the 650, but lots on here are using the DS450 shocks, easy fit apparently.
LTR450 shocks will fit also, although you have to turn them around so the reservoir faces forward (too close to radiator otherwise) & spread the top mounts about 2mm each. They are a marked improvement over the stockers. Search it up, there are heaps of posts on shockswaps on here.
i run trx450 shocks on mine for a wile, and while they were short the front end sat at the same height that it does now with fox evols on, they could do with slightly heavier springs, but if ur a light bloke then i wouldnt worry too much, they are a straight bolt in shock