but the tried and tested methods for any bike will see you through the first stages. Check for obvious signs of damage, have the ends of the mirrors been scatched against a wall, has it been dropped whilst moving it around (in the garage for instance), look for scuffs and scratches and touch ups, usually a good sign if someone is prepared to touch up stone chips but if you spot fresh/different shades of paint anywhere on the top or sides look closer. Ask pointed questions like has it been dropped/crashed/damaged in any way, and always ask the bare faced question "Is there anything wrong with it?". Check for general mechanical wear and tear, have the tyres got a good amount of tread left, how many miles has the bike done on them, same with chain and sprockets. See if you can pull the chain away from the rear sprocket, if you can it'll need replacing. Get them to start the bike from cold, most Dukes are happy starting warm/hot but dislike the cold so you can hear any quirks when it's fired up. They all misfire and stall occasionally until the first service but should be ok after that so check for smooth running, when th engines ticking over nice and warm feel the throttle grip for free play, turn it so you take up the slack and give it a short blip, make sure it doesnt rev up high but ensure it picks up quickly and smoothly, take it for a short ride if you can, but be very careful about riding a bike so different to what you may be used to. Try not to let the excitement of such a beautiful bike distract you from HAGGLING

Hope fully somebody with specific 749 knowledge will post a reply to help out more.
Good luck J!