Actually, they weren't thinking about that at all. GODZILLA VS. KING GHIDORAH was a big hit after the BO failure of BIOLLANTE, so they figured on pairing Godzilla off with his greatest foes. When the found out it would be too cost prohibitive to obtain King Kong, they thought of employing a revamped Mechani-Kong (from KING KONG ESCAPES), but they figured that they would also have to pay rights to its use as well and the project was dropped.