There were big changes between years, with the newer years being much lighter and having much more torque.
The early ones were really cb350's with a different style, the later ones got a lighter frame, lost the electric start and 40 pounds, and had different cams.
I would love to have one.
Parts are hard to find, but a lot of cb350's were made.
I had a cb350 and I had a friend who also had one, and it would do 90 mph indicated, it was a bit faster then my powroll 300cc xl250 with a cam and a super trap exhaust on it.
And I bet you can get a little more power out of one over stock without much trouble.
I suspect the suspension was better then some bikes I dirt rode, and better then the 69 Daytona I had a blast with a few years ago.
I never rode an sl 350, but its sort of my dream dual sport bike.
I hit the lottery and I am getting a restored like new one. Or 5 of them.