Like Casey has already said , not much profit if any in trying to sell those kits , so build 'em !
Even if they were a bit rare , build 'em ! Isn't that why you bought them ?
As for the decals , never take a chance with older ones . Always coat them with a sealer of some kind , I use Testors Decal Bonder but a good clear will do the same thing . I also scan the decals before I do anything , just in case !