I can't imagine any PC house not being able to use photo artwork to produce the boards. The one thing a gerber file does provide is the drill file with drill sizes, so you would need to take the padmaster and identify the different hole sizes. The PC house will normally enlarge the sizes you come up with so that the plating and solder reflow process brings the holes sizes down to what you specify. If indeed you have the master 2X or 4X layouts, an engineering photo lab should be able to reduce them to 1X artwork. BTW, I also have the photo artwork for several Polymorphic PC boards.