Tele, that theory makes sense as one thread in a tangled skein... and yet...

The Monsters had already been moved to the U.S., with Alucard, Kharis, & the A & C film. Also, though Uni moved away from them, other films using similar monsters were made by other studios in that era: THE WEREWOLF, RETURN OF DRAC, FRANK. 1970, PHAROAH'S CURSE.

It could've been done. They just chose not to do it.

Best,
-Craig W.

Monsterkid since the Kennedy Era