I will add just a couple of comments here. First, I believe that the distance between the holes in the u-bolt plate are the issue here, not the u-bolts themselves. If something doesn't fit, I'd suggest modifying the plate, NOT the springs. You do not want to weaken your springs, plus it is a giant PITA to try and grind through spring steel.

Also, it is not advised to reuse old u-bolts as they have some "stretch" in the threads that keep them torqued down the first time they are used. I am not saying that no one reuses their old u-bolts, just that it is not advised. New ones aren't that expensive anyway.

It sounds like you can contact Sky or Rockstomper and get exactly what you need though, just let the vendor know what you are planning to do, it is not that uncommon a swap.