Be careful with the 9600's core, its very small and fragile. To fit the heatsink on, drill 2 holes in the heatsink and run bolts through with springs on them to prevent overtightening. You might even be able to run passively.
you shouldn't have a problem fitting an amd hs on a 9600pro. while i was waiting for my wc to arrive, i put a p1 hs on my old 9600pro for temporary use. with the hs, and a small fan, i got about 10mhz more oc on the core than i did with stock cooling
 just remembered unoid's 9600pro modding page