Pre 1975 1F engines have a different air cleaner assembly than the post 1975 2F engines. On the earlier engines the air cleaner has a bracket that bolts under the first two head bolts on the left side of the engine. Then a much larger and deeper air cleaner assembly bolts to this bracket and runs back to the carb, rather than on top and over the valve cover like a 2F. The air cleaner element is actually the same one used on the 62 and 80 series cruisers.
Often times the bracket has been removed when people put a holley or weber on, and when changing back you are faced with a challenge of how to get the bracket back on without harm to the head gasket.
Poor design in some ways, however, it allowed a person to take the valve cover off a 1F, while it was running without taking anything else loose to perform valve adjustments, as is recommended in the early manuals. When you run an engine without the aircleaner, it changes idle speed slightly, and effects your tuning. In reality it is next to impossible to adjust the valves with the engine running.
To add, the two bolt holes you pictured were actually used to hold the coil on early F engines. Later on they are used for the 2F aircleaner assembly.
