EGW sells a one piece picatinny rail that will fit Pre 64 Model 70's. Certainly easier to get good eye relief using that type of rail.
https://www.egwguns.com/scope-mounts-rings/standard-rifle-scope-mounts/?brand=778Pretty sure that Warne sells a two piece picatinny bases that will work too.
Murphy Precision makes a high quality base as well.
https://www.murphyprecision.com/scope-bases/winchester/