Interesting! Right from 'my' era (late 1970s), the epitome of the dreaded 'Universal Japanese Motorcycle' (UJM) concept: the top one is almost certainly a Kawasaki Z750, circa...1978? The type ran into the early 80s -have a look here:
Z750
The second object sports a 'Turbo' graphic; this was an early 80s obsession, but as far as I am aware Kawasaki did not bolt a hairdryer onto their 750 block until the later GPz750 (1983, too late for the Falklands!) This was a more modern design altogether:
GPz750 Turbo
Maybe yours is a one-off custom? It happened quite a lot; big-bore Suzukis were popular among third-party turbo-ists.
As to scale...absolutely no clue. Sorry.
Great to see these in plastic, though, thanks for showing them and allowing me to wallow in sentiment!