Hello,
If your engine is indeed an orginal '62/'63 406 is has mechanical lifters. The 406 blocks DID NOT have the lifter galleys drilled to allow the use of a hydraulic cam. I would first adjust the valves and then install a mechanical
oil pressure gauge as Mr. Fixit suggested. If the pressure is still low (your
oil pressure is not terribly low but is lower than normal), change the
oil and filter. Depending on the viscosity oil you are running you can go up one weight of oil (5W/30 to 10W/40 or 10W40 to 20W/50) and see what happens. If you do end up having to go through the engine
remember that pre-'65 FE blocks use a different crank thrust bearing than the '65 and later.
HTH
--Mike