Rob:
I have another candidate for you: koa. Your core looks very, very similar to the koa core on my '76 Series I (76-414), and to my inexpert eyes it looks more like koa than cherry. According to Mica, the cores back then weren't nearly as standardized as they are now, and koa and cherry were commonly used. And, to make matters worse, when she pulled my wood card I learned that my neck was made of birch - not maple. That was pretty common in 1976, so yours might also have a birch neck.
Steve