Lee:
Welcome to the club. You've got a very sweet instrument there. It is what is now called a Series I guitar. (I believe at that time it was the only model Alembic was making. It became the Series I later on). From the body shape, I'd venture that it is a medium scale - 24.75, like a Gibson. Assuming the electronics all work and you have the original blue box power supply and case, it would likely bring about $2200-3400, depending on condition (your's looks pretty sweet). It's a little difficult to put a hard value on these as they come up for sale sporadically at best. One of your vintage might show up once or twice a year at most on eBay, and might not show up for a year or two.
Bill, tgo