My Sportster desperately needed better shocks as it might as well have been a hardtail stock. To review clearances I removed both original shocks with the rear end jacked up and measured eye-to-eye mount distances with a very large sliding caliper over the range of allowable travel. Too short and you start hitting frame/fender with swing arm/tire, and too long and the axle may hit the muffler.
The drive belt is at maximum tension when the rear axle, swing arm pivot and drive sprocket centers all line up. I never bothered checking what lengths will and won’t work on the SCR950 as I’m happy enough with the stock shocks. Remember it’s not all about maximum travel as too much may cause wobble under G forces in turns without the right dampening. Let us know what you find out. Cheers,