Like said, if your going to use it as a regular rider, go with the '75 and later. I was a Suzuki tech when they were new on the showroom floor, and have ridden dozens of them over the years. Very sturdy bike, and about as dependable as it gets for a 2 stroke large roadbike.
They are solid and neutral in handling, unlike a twitchy RD or a wobbly and wheelie prone Kaw tripple. Not a exciting ride by any means, but a great platform for a all purpose UJM kinda tourer. Brakes are very good for what they need to do. The seat is kinda wooden and would be best to have a custom seat made up to improve the ride comfort.
A big plus is the water cooled engine is very quiet, and stock puts out a very smooth power delivery, its not like a typical 2 stroke powerband, its not very peaky, and pulls somewhat like a 4 stroke when opened up in the midrange. Very usefull power curve . They dont have alot of handlebar buzz, and your footpegs and mirrors dont vibrate either.
If you really HAVE to go with pipes, dont do the 3 into 1 Ocelot pipe, they dont work well. Find a set of J & R's if you can.
Its a heavy, solid, neutral handling bike, not like the Kaw's or little RD's of its day. Think of it as a older Honda CB 750 with a nice smooth 2 stroke tripple tucked in it.