Since I totaled the Kat 750 I have a rear rim & shock I can use on the GS500.   I'm not sure what size the rim is wide and will have to wait until I can see it again to find out.

Tires a new 160/70/17 I think. Does anyone sell the spacers needed to do this. I can't work on it for 6-8 weeks but want to get ready.

Rear Kat wheel is 3.5".  Stock tire size is 150/70/17.  Have you heard of this swap being done B4?  I have heard of swapping the shock from a Kat 600.  I have a spare 750 shock I was thinking of using too but it may need some tweeking to make it fit.  You may have trouble getting a 150 tire to fit inside the torque link for the rear brake.  

What are you doing with the rest of your 750?

The 89-96 Katana 600/750 share the same wheels with the GS.

Happen to have a front axle with spacers and the clip-ons from your Kat that you would like to sell?