Check the restore projects on this forum. An OEM style K0-K6 with 4-4 are really nice!
It also depends on the person and old memories. The earlier tank design is something extra for me when I remember the old bikes before I was allowed to drive one. K0-K2. I have 2 fresh tanks with the later decals K3-K6, original tank for my K6 need to be redone and my old service tank can be repainted in K1-K2 style, gold as I remember the fist CB750's I saw..
Kawasaki Z1-900 72-75, Z900-76 OEM style are OK too. Z1-1000 77 had same design here except rear disc brake and still spoked rims.