The Yamaha 550 Vision was an OK bike for me in those days (mine was a 1982). It was a little lacking in overall power but responded very well to opening up the air box (by drilling a whole bunch of holes in it) and rejeting the carbs and I had bought a Spec II exhaust system which needed a crossover tube added to it to make good power. It has more mid range power than the 600cc 4 cyl bikes of the day and still had a 10,000 rpm redline.
The only thing that I didn't like was that the wheels were very narrow, so I couldn't put on good tires. Also, the handlebars are a little strange with them being part of the top triple clamp. I had made an aluminum part to replace them on the triple clamp and changed to clipons (I was into street road racing or canyon carving in those days).
It did have shaft drive for lower maintenance. I always got about 55 mpg out of it, about the same as my Ninja 500R.
I had always thought that it needed two more cylinders and in 2000 I bought a 1200cc 140 hp VMax. That solved my horsepower need for a few years.
I never had any problems with the bike. so I'm sorry I don't have any info to give you (except opening the airbox and rejeting the carbs).
Good luck with your project.