You'll need 3 measurements, overall length full extension (full droop of suspension), full compression (suspension fully bottomed out), and nomunal ride hight length (length mount ot mount at normal ride hight). Then those will have to be cross referenced to get the closest match. I'd add about an inch or 2 to the full extension and full compression to give a little margin, better to have more shock stroke than you need that bottom out.
Who did you get the springs from? I wouldn't be surprized if the don't have shocks just for this application and those springs.


Bill Burmeister