I pulled up a picture of a 1982 model. I don't remember much of the CSR series, but it looks like Kawasaki's budget-level cruiser model. Like Suzuki's L-model, it has the stepped seat, high-rise handlebars, wire wheels, and drum rear brake. It wasn't much back in 81, and won't be much now.
Why not get a superbike from the 1980's? They wouldn't be as fast as today's 600's, but they may have been owned by an enthusiast who cared for the bike and updated it. I have a 79 GS1000 in the garage with a zillion mods. It rides like a Cadillac, and will surprise many bikes in the corners.
An 84 Ninja 600 or 900 is only three years younger than the 81 but would be light years ahead. I actually ran both on a track in 84 when they were introduced.