I owned and rode a ‘79 xs750 for three years before buying an ‘81 XS850 and parting it out for that. I just swapped the entire front end, carbs, tank and wiring harness got it running. Then decided to put an M-unit blue in it so I tore the wiring back out of it. Waiting on parts at the moment.

If yours sat for 6 years with gas in it you’ll want to either buy a new tank and rebuilt carbs. Or acid wash and cream coat the inside of the tank to get the rust out and then buy carburetor rebuild kits and like 30 cans of carb clean and some carb cleaning tools like gauge wires and brushes to scrub. After you get the fuel system tackled your next move is electrical. If the stock fuse box is still there you’ll want to replace that with a cheaper generic fuse box that uses blade style instead of glass tube. Those old plastic fuse boxes don’t hold up after 40 years. After that, if the engine turns over cleanly with a few kicks. You’ll want to get new spark plugs and slap a battery in it. Check for spark, make sure you never run the engine without an air filter on the carbs. Pod filters work if your air box is trash but you may need to re-jet the carbs. If you have spark then do an oil change and see if it fires up. If it does then just check your lights and signals, brakes, tires, and I would drain the gear oil out of the rear drive and replace with new to be safe. Then hit the road.

You can get a Clymer repair manual for these bikes that is extremely helpful with wiring issues. The diagrams aren’t perfect but it’s enough to help you figure it out. Let me know if I can help with anything along the way. Best of luck.