I'm not sure what is best either.  From what I have read it seems race bikes favor a more linear nature, whereas street bike tend to use progressive wheel rates.  I would enjoy learning more about what typical race and street bike use.

I did a little more work on this project, with some mixed results.

1. It looks like the dogbone from the 06-10 GSX-R 600 & 750 is mostly compatible with the RGV linkage, and it's just about the perfect length to preserve the stock ride height using the RGV swingarm. I prefer this approach to re-welding the upper shock mount, as it will keep the linkage at it's stock orientation, preserving the damping rate curve. The linkage looks like it will bolt on by swapping the RGV inner spacer into the GSX-R linkage (same OD, and ID, different length.) The lower end of the dogbone may need to be machined down to fit the GS500/RGV rocker arm.

2. It looks like there are all kinds of clearance issues with the RGV swingarm, especially with a R6 shock installed. One of the chain guards hits the R6 reservoir, and it appears that the upper brace of the swingarm will hit the piggyback reservoir under compression. These first issue is easy to resolve - remove the chain guard. Second issue is harder - and may only be resolvable with a shock swap. I have an 06/07 R6 shock installed. An 08/09 shock is slightly different, and may offer the clearance we need.

3. As mentioned earlier, the GS500 rearsets need to be offset to clear the swingarm.

4. With the spacers that Gerry fabbed up, the RGV swingarm barely clears the exhaust.

5. It looks as if the passenger peg brackets interfere with the RGV swingarm. Right side should clear on my bike, but left will not. Left peg is going to need to be cut off, which I am not pleased about.

My general feeling on this project right now is: It's probably not worth the cost.

Nice find on the GSX-R dogbone.  Looks like a nice cast aluminum piece.

So is the GSXR dogbone part might be too narrow to fit the GS or RGV rocker? Both the GS and RGV (VJ22) rockers are about 85mm where the dogbones attach.