You can try one out if you want to open the pack and not keep it as a collectible. Plenty folks like to shave with NOS carbon blades. Just make sure there is no rust on the blade at all, especially the edges. If you have a blade stropper or sharpener such as the Twinplex or one of those glass/ceramic dealies, it will help get it ready. If not, you can strop it on the back of your hand a few times. It won't tear you up, just shave with care. You may find it is just too dull for you like they are for me.
Personally, carbon steel blades don't work for me, new or old.
You can shave with it, if there isn't any rust present but why? It not like there is a shortage of sharp modern blades available. My advice just keep it as a curio.
They are far more valuable as a curio with sentimental value than as shaving blades. Unless they've been stored in oil, I doubt they would shave well at all. Even if they have, I doubt they would shave as nice as modern blades.