is it the 9L7 on 1 head and 9K20 on the other?
There should be a longer number on them something like this
D0AE-6090-E 70-74 351C 2V heads In Valve 1.946" 2.046" Ex Valve 1.6495" 1.6595" 78.2cc
D0AE-6090-G 70-71 351C 4V heads Valves 2.195, 1.715 62.8cc Closed Chamber
D0AE-6090-J 70-74 351C 2V heads In Valve 1.946" 2.046" Ex Valve 1.6495" 1.6595" 78.2cc
D0AE-6090-M 70-71 351C 4V heads Valves 2.195, 1.715 62.8cc Closed Chamber
D0AE-6090-N,D0AE-N 70-71 351C 4V heads Valves 2.195, 1.715 62.8cc Closed Chamber
D0AE-6090-R 70-71 351C 4V heads Valves 2.195, 1.715 62.8cc Closed Chamber
D0OE-B 70 302 Valves 1.78, 1.45 58.2cc
D0OE-C 70 - 74 351W Valves 1.84, 1.54 60.4cc
D0OE-6090-R 70-71 429CJ & SCJ Valves 2.24, 1.72 73.5cc Adjustable Rockers
D0VE-C 70-71 429 460 Valves 2.09, 1.65 75.8cc
D0ZE-6090-A 70 Boss 302 Mustang Valves 2.19, 1.72 58cc
D0ZE-6090-B 70 Boss 302 Mustang Valves 2.19, 1.72 58cc
D1AE-GA 71 B0SS 351 Mustang Screw in Studs Guide plates Valves 2.19, 1.71 75.4cc
D2OE-AB 72 460 Police Interceptor
D2OE-BA 72-74 302 Valves 1.78, 1.45 58.2cc
D3ZE-AA 73-74 351C 4V heads Valves 2.04, 1.66 75.4cc
XE-145488 429 Police Interceptor Aluminum Experimental Part