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To add to what has been said, per FoMoCo design, the oil 'overflow' from the two rockerarm shaft overflow tubes has purpose:
The overflow tube on the driver's side is to be located at the rear of the cylinder head (near the firewall) and that oil overflow tube is directed toward a pushrod hole that enters the rear of the valve lifter 'valley' area and will provide lubrication to the distributor gear and area where the end of the distributor shaft is supported (housed) in the engine block casting.
The overflow tube on the passenger side is to be located at the front of the cylinder head (near the radiator) and the oil overflow tube is directed toward a pushrod hole in the cylinder head that enters the front of the valve lifter 'valley' area and through openings in the front of the block casting provides lubrication to the camshaft/crankshaft timing gears, and the timing chain.
Okay?
NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York