Powders change over 40 years, just like people do.
So do methods of measuring pressure - some of the old manuals estimated pressure by looking at primer flatness and maybe miking expansions rings. Neither method is anything like precise. Then came the copper crusher method, which was better, but not perfect. Copper crusher could only be done in test barrels, too - not possible to use the method in a real world rifle.
Now the ballistic labs use much more accurate equipment - usually a strain gauge set up that measures in PSI, and can be used on the same model rifles that people can buy over the counter.
Some loads have been lightened over the years, and people claim it's "because of the lawyers". Nuh uh. Powder changes (and bullet and brass changes, too) and more accurate measuring capability now give us much better info on what's a safe load.
Fish, your old load might be fine, with the components you used at the time. If you have some left, they should be safe to use.
On the other hand, if you're going to do some loading now with new components and powder, use current data.