I think the 6x makes a great varmint scope, especially on a rimfire rifle. I had an old Weaver 6x on an equally old Winchester 69a, and it was a lights-out combo for me. Killed lots of small game and miscellaneous varmints at ranges further than I care to admit. The best part about the Weaver scopes, to me, is the super fine crosshairs. I have an old Weaver K2.5 on a 572 Fieldmaster right now, and a K4 on Pap's old Mossberg 251c, and absolutely love the crosshairs on both. The old Weavers work so well that I'm looking for another K6 for my BRNO #2, but I can't find one at what I consider a "reasonable" price.
So yes, I would definitely put that K6 on the 700. They were the "original" varmint scope back in the day, I can't imagine why it wouldn't do just as good today.
Mac