Roy,
If the bows have the same riser shape and riser length, and the limbs match up like they were made on the same form... and the only difference is the string groove location on a slightly longer limb tip... well...
Guess all Bear bows of different lengths listed in catalogs that I can think of actaully have either different shape risers or different limb shape, rather then just length of the tips.
Sort of a gray area as far as classifying what is really what...
I have several 60" 1959 Kodiaks that are all marked 60" but have slightly different length limb tips with string grooves in slightly different locations, and require slightly different length strings. Kind of a nightmare sometimes when reusing strings.
With the slightly longer limb tips, it is understandable why a 62" string seemed too short to someone at Bear and why they wrote 64" on you Grizzly.
The fact that someone at Bear wrote 64" on your 1959 Grizzly makes it a unique bow.
It is great that you and Cody took the time to figure out what the bow was.
Thanks so much for sharing the Grizzly, it is certainly educational to see these unusual bows.