I'm wondering if anyone here can direct me to a good internet resource or help me to identify approximate vintage and Model Number of one of my Sigmas. It's an oldie from Japan, missing the label from inside, so I'm at a loss to identify it.

It has the old Greek Sigma character on the headstock, with "Sigma" spelled out just below. It appears to be cedar top with Rosewood back and sides, with white binding around the body edges and headstock, but the fingerboard is unbound. It has plain generic sealed tuners, (like my old Ventura), and a sunburst finish on the back of then neck, but natural everywhere else.

The rosette and pfurling around the top edges are plain, no abalone, and although everything seems solid as a rock, the strings are a mile high off the fretboard, leading me to wonder how to bring their height down to a more playable level. It has a wonderful Martin-like boomy, percussive tone, and I think its worth the effort, but I sure would appreciate if anyone can help me to identify it as to model and approximate vintage.

Thanks.