Take a lookie see inside the tank. Look for rust. If it's clean that's great. Make sure the engine isn't locked. Assume you'll need to go through the carbs, get new tires, recondition or replace the manifold rubbers, rebuild the MC and caliper in the front, maybe need a new chain and sprockets, battery, electrical work, possibly some seals.
Sounds pretty nice... I'd give from 6 to 7 hundred for it.