I have a short action PBR in 308 Win. It was one of the last M70's assembled at New Haven.
I own several pre64's and controlled feed.
FN extended the bolt shroud to protect shooters from a gas leak, so that is an improvment. Still, I suspect that gas from a pierced primer is still going down the firing pin shaft right in your eye. (the M98 is still the best ever in gas handling)
There are minor differences between the old and new. Bolt may interchange, but not shroud/firing pin assemblies.
Overall, the machine work and part fit is excellent. I believe FN is a better manufacturer of rifles than Winchester ever was. The pre-64's are examples of 19th century "file to fit" technology. Lots of file marks, parts don't interchange without fitting, assuming the part can be fitted. The classic actions were good to very good, but I believe these FN actions are the best.
The action is slick and smooth. Bolt lift and manipulation are excellent. I like the claw. I wish they had simply copied the original pre 64 action (but extending the shroud) as that design is the best of the M70's. Virtually all changes have been for the worse. Too bad Winchester New Haven manufacturing was a good example of bad manufacturing.
I don't like the four round magazine. If FN ever offers a ten round mag, maybe that might change things. But right now, you only have four rounds in a 308. The stupid magazine cuts my fingers loading and as you insert rounds, the the top round will slide out the back. This creates a jam, is a mess to clear as I don't want to bend anything on this $50.00 magazine. (a freaking rip off!! :barf
Oh yes, magazines are hard to find.