57 Windsheild header & door dimensions

Does anyone have the factory specs on the distance and how I can measure the correct distance/location windshield header for the roof to screw into the windshield header? Though there are roof adjustments, the cowl to floor supports have rotted allowing the header to lean inward. This also affects the door width and alignment. When I go to repair the rotted floor and cowl supports, I want to be sure it is moved to the correct position. Any information is greatly appreciated.