Dendo,

A charge voltage of 14.8 is still within normal high limits so I wouldn't worry about that. I would do as BC52 recommends and see what that meter attached to the battery reads when you do your little draw down test.

I don't know what kind of charging system a '63 has, but it might not be able to see system voltage well enough to react and kick in in short order. Your dash volt meter, however unlikely, could have a very poor connection to the charging system. If you compare a test meter reading at the battery with the dash gauge reading it should give you a direction to go.

If your rig uses a voltage regulator with either a 10dn alternator or a generator, I would be real suspicious of it.

I would also look at the brushes on either alternator or generator.

Stuart