Ford trucks were restyled in '73, so the Moebius kits would not be your best course of action. Right now, the AMT '78 Firestone pickup is your best starting point, with the addition of a resin '74 grille (Rookie Resin?). Note that the AMT Firestone kit has the "Camper Special" extended wheelbase long bed, so you will have to convert the wheelbase yourself, or find a resin long box with standard wheelbase. (I think MAD Resin did one, IIRC?) Or, if your Dad's truck was a flareside, you can add the Moebius '66 flareside box.
Hope this helped.