It depends on which
Pachmayr mount is on the gun. I think they called the swing away style the “Lo-Swing” mount. They made some that mounted in the factory holes and some that required additional holes and may have even required relieving of the wood.
An early 1950’s vintage Model 70 should be factory drilled front and back and have two plugged receiver sight holes on the left rear. This similar .270 (191,3XX) has a Stith mount in the existing holes and didn’t require modification. It’s value is the gun plus the optics ($1500+). Additional holes is a big hit on the gun, but you know that.