I think it's interesting that you're holding out hope of actually finding a 49-year-old plastic ship model.
I've got a couple of built models from the early sixties, both AMT cars, which are more inherently 'survivable' than a full-rigged ship model.
I had a small Revell Constitution that I was particularly proud of that was on a bookshelf in my parent's living room when I left for college in 1971. They moved to another city a couple of years later and unfortunately my ship model didn't survive the move...
Mark
Mark