Last time I was looking around everyone was using the 5100 series shocks. But I’d probably want the heavier 5125 in front and 5100 rear since the weight difference front to back. Your best bet is to go with your initial measurements and find the correct shock length. It will be way better than what you have now either way. Or should be. I know the ranchos are mediocre at best even when new. At least they slow down the bounce a bit as I rode around for about a week without rear shocks when I was doing a axle swap and waiting to put new shock tabs on. That was a experience I would not want to deal with again.