'77 F-100 302 need some valve specs

Assembling a 1977 F-100 302, does anyone know what the clearance should be between the rocker arm and valve stem? Also, does anyone know the rocker arm ratio(difference from the push rod to the rocker arm pivot point vs. the distance from the pivot point to where the rocker arm contacts the valve) on this engine? It seems like this should be simple to measure, but atleast for me it isn't. I need to know this to accurately order the correct length push rods if needed. Thanks in advance for any replies.