Seeler played in a wide-range CAM role behind Müller in 1970. RW was occupied by Libuda or Grabowski (and maybe someone else I've forgotten, Germany had truckloads of wingers back then).
As I see it, you have three attackers who all were at their best in some sort of free role. That means they occupied different position over a game, yes - but I'm not sure the result of playing them together is a situation were all positions are reliably covered as they should.
Maybe a primary balance player instead of one of them would have been better for the team shape. Someone whose main task is to react to the alphas and their movement, which in turn frees up the main players as well. Seeler was an exemplary teamplayer, so he's the natural fit there, but I'm not sure that's really the answer.