There are just so many different Weems calls that more info would be needed.
Production started around 1954 so a 60's call is fairly early. The plastic, two part, "All-call" came out in 1960 so if that is the model it could be very collectible,especially if is says "patent pending".
The best way to find out for certain would be to talk to Jay Nistetter at "Rhino Calls". I might be able to look it up in his book, "Predator Calls,The First 50 Years", it's really the holy book of predator calls!
Nikonut