ORIGINAL: RC-FIEND
Wood that is properly stored does not warp or rot. Woodworkers do this all the time. The key is to keep it properly stored. If the kit has been opened and the wood put back all jumbled then yes, it's probably going to warp. If the sheets and other stock are still bundled and are flat on the bottom of the box then they will remain straight. I too have several old kits and when I look at them the wood is still in excellent condition.
I am not saying there are not ways to preserve the wood or balsa if you will , but my goodness a model that is 40 years plus, IMHO is just scraps. I haven't even lived that long yet never mind building a model kit that was made before I was born and then putting a torque throwing engine on the nose and then taking off for a flight. Has it been done ? maybe but I would rather just buy a similar kit that was made in the year I am currently experiencing.
That's cool, it's better to leave the old kits to those who appreciate them.
Personally, I like both old and new.