The 600RR shock will definitely not fit on the F2/F3. The F4i shock works and raises the rear about an inch and a half. Its not bad. If you talk to MoreRR on CBRWorld, he says his best geometry was raising the rear about 37mm or so and lowering the front about 17mm. Thats a pretty drastic change but it works well for him and he's a bike designer/engineer/mechanic. Im not saying his word is the bible but you can do whatever you like. Getting the forks redone is around $150 but thats not including the valving and parts such as seals and fluid. I just did mine last weekend and all i paid was for two new sets of seal, dust seals, and a bottle of fluid. There's a great write up around somewhere on rebuilding and revalving your own forks. Its not hard. Just messy.

 

after looking at a f4 shock as well, it looks almost like the f3 shock so im assuming there is no real performance advantages? other then it raises the rear up a little bit.