Not sure about the 1975 rifles. At one point all 70's were long action. Not sure when they started making short actions. I'd make sure before ordering.
FWIW I truly despise any of the mounts that are windage adjustable and would never think of using one unless my scope mounting holes on the rifle were drilled off center so badly I couldn't mount a scope without using them. That is what they are made for. If your mounting holes are drilled correctly there are a number of much better mounts.