I hope you manage to find the other two, particuarly the green supreme, that would add nice balance to the picture.
After looking through what little I can find, I have a feeling the Green supreme is a twin with a revised coil, while the gold supreme is the same as the green, but with hight compression heads, and a suitable adapted muffler.
The coild revision came about due to the high failure rate of the Twin coil, due to this high fail rate, there is a good chance the twin engine you have would count as a supreme engine, as back in the late 70's, if the coild died (whitch it often did) the repair shop relaced it with the new, revised coil.
So many twins are in fact defacto Supremes.
