I always liked the aircooled BMW's of the 70's.
But I did wonder about the heat on the shins after a couple of hours in the saddle.
I don't think an old Sporty is what I'd recommend as a bike to be driven regularly. A late model Evo Sporty, maybe, depending ... Newer rubber mounted , yes. That's a nice bike.

But if it's to be part of a "collection" and rarely driven, heck anything that will go up in value will fit the bill.

I have a 1975 Kwasaki Z1B I'm looking to sell and expect to turn a profit on it for the 3 years I've owned it.

The OP never mentioned experience or intended use, so further input would help.