[Arran]

Hide glue in the 1950s and 60s? Heck no, that stuff was largely displaced from the furniture industry by 1950. Although maybe some small time outfits were still using it, it was by no means the most common glue, why would a furniture factory use it when they had less expensive and more reliable PVA and phenolic based glues available? The reason I know is that I purposely left a post war radio-phono combo outside over the winter once with the hope of salvaging the veneer from it, some lifted a bit at the edges but that was about it, the lumber in the top curled like crazy though. I've never been able to get veneer to stick back down by heating it, regardless of what glue they used, because there just was not enough left to make it stick down again.
 As for contact cement, I have used to to stick down veneer patches in the past, and I never had any issues with bubbling or offgassing through a finish,nor the patch moving around. I was told that the main issue would be that it might dry out and fall off with time, this is the neoprene solvent based stuff, not the water based latex stuff. I prefer to use yellow PVA glue whenever I can, and it seems to do the job, especially the structural repairs, with veneer you don't really need much adhesion to hold it down. PVA will also let go with heat just like hide glue, there are some people who use it like hide glue for just that reason, but unlike hide glue it doesn't crystallize and fall apart on it's own in cabinet joints.
Regards
Arran