I had a bunch of NOS SunTour Sprint 130/160mm cranksets. I sld most to Harris Cycles some years back, and they may still have a few. Otherwise, I might still have one or two tucked away someplace.

I don't know how tall you are, but unless you're shorter than 5'6" or so, or have a low BB, or limited front wheel clearance, odds are you don't need 160mm cranks.

There's lots of "science" about crank length, but bikes have been around for over a century, and the 170mm "standard" is the result of many years of evolution. Consider also that it evolved when the average height was far shorter than today. In fact many argue that the increase in height argues for longer cranks.

I you've been riding 172.5 cranks and don't find the low/high positions straining you or giving you the "knee is in my gut" feeling, you're probably fine staying with them.