You may want to change the cams and put in ST2 or 900ie cams in it, but don't bother looking for an ST2 engine to drop in. It's liquid cooled, you might have a problem there, last time I checked, an SS didn't have the plumbing for that.

Check these pages for more info on cam specs and valve specs for your particular engine.

http://www.moto-one.com.au/per....html
http://www.moto-one.com.au/per....html

Good luck with whatever you decide to do with it.