ok here's some real life experience. I had this same exact problem from a used set up. the overall length was 12 and a half inches, but what you really need to look at here is the length from the pivot point for the fulcrum the end of the fork. I was given the wrong fork and ended up having to get a correct one. Again you should have like four inches from the fulcrum point to the end of the fork not three and a half.
but double check those measurements with somebody who actually has the correct one.