It is possible but you also need to cut the 41 degree cone and then index the extractor cut. The Classics will screw onto a pre 64 action just fine but I believe will index 180 degrees out. I may be wrong on that. That is a pre 64 Win 70 barrel as it has trade mark spelled out not the circled R from 1963 on.
A sample of one that I did (classic fwt barrel onto pre 64 action) just needed the extractor cut opened up a bit to fit perfectly. (like about the thickness of a dime or quarter). Headspace was fine.
