If there is an Eagle dwg you might be able to convert it to FZ, but the way I would do it is draw the 120.24x77.2mm green PCB in Inkscape, get the screw terminal svg from the part in FZ and lay them around the outside, and then get the MEGA PCB svg and delete lines not needed so it’s just headers and place that accurately on the green PCB. If you want all those prototype pads you will have to set up a grid and place them.
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