For what it is worth, all Remington 721, 722, 700, 600, 660, model 7, 40x, XP-100, all share the same nominol tenon thread dimensions, in diameter and length.
You can take a 308 barrel out of a 1968 model 600 and screw it into a 1995 long action, and aside from some minor headspace differences, which must be checked, it will work.
The bolt faces will vary depending on whether the Rifle is chambered for a .375 case head, (223), a .473, (308), or a magnum, (300 Win Mag).......jackie