Glad to help, Konrad. I long ago intended to merge those two scripts to find both Hi and Lo in one go, but never got around to it. These days, I tend to just scan the velocity tails in the PRV, and estimate a range that encompasses everything.
I have to reiterate that the the Event Inspector really addresses most cases of simple velocity interpolation. It's only when you want to both move the center and change the "dynamic range" in one go that you would need to use Interpolate (a.k.a. Find/Change). But it's easy enough to do it in two steps with Event Inspector.