always thought they looked like a 748 on steroids.
It probably was. Some of the first Japanese motorcycles were direct copies of British bikes. I seem to remember that one of them was so alike (a Kawasaki 650 twin) that it even copied the BSA three-rifle logo on the timing case.
And then we have the VC-10-ski, the Concord-ski, the 146-ski.....
ST