Hi Stevie,
I'll just give you information I know and checked. (I'm basically an American rock fan and am not an expert on this.)
I know the Golden Cups because I lived in the area where the club Golden Cup was located when I was a kid. The guys or some of the members used to play dance parties.
The member who formed Godiego is Mickey Yoshino, the keyboardist who left the Golden Cups for study at Berklee in Boston. He returned to Japan in the 70's to form Godiego.
Although the Golden Cups are recognized for pioneering Japanese rock in retrospect, Godiego was a bigger commercial success in their days. I think that many Gold Cups-related people and former members participated in production, etc., for Godiego.
The genealogy (in Japanese) is found here:
The Golden Cups
Godiego music is here:
http://columbia.jp/~godiego/sound.html
Their biggest hits were Monkey Magic, Gandara, Beautiful Name and Galaxy Express 999.
I still see Mickey Yoshino and the Godiego vocalist Takekawa Yukihide on TV sometimes. Oh yes, and Godiego had a reunion concert in 2000 and the Golden Cups reunion was held this year (very recently, actually). I think there is a Golden Cups film retrospective currently showing in Japan.