Dava-the power difference is noticable, but it's almost all due to the change in racquet technology. If you ever get a chance watch Navratilova-Evert in the late 70s, early 80s and late 80s. They hit much harder at the end of the 80s, yet Martina and Chris peaked earlier than that.
If Steffi, Monica, Venus, etc hadn't come along some other power hitter would have-metal (and much wider frames) made it possible.
IMO. With rare exceptions a champion in one era would be a champ in another.