To me it looks as though 64.4 is very good too. Less vertical in the groups. Adjust your OAL to tighten the group.
63.1 is good too. Same thing with OAL. This may be great target load or hotter weather load.
Then stretch it out over a distance and see....but I'd find the best OAL for the 64.4 load. That's my 2c.