Mysterious 1964 dart rag top????

64 Dart ragtops were fairly common, and about half were 273-2 cars (273-4 came out in 65). The four speed makes it a bit more scarce. Even then I'd bet there were several hundred made.

As for whether or not it is worth saving, that's a bit tougher. You could probably part it out and break even for $1500. It will probably never be worth what it would cost to restore, even if you do most of the work yourself. BUT it would make a great cruiser with a mild engine. Body/trim bits are hard to find for the early A's, so don't discount the possibility of a replacement body and/or another 6 cyl parts car to make a good driver.