Low oil volume

Pull the shafts, pull the distributor, and intermediate gear, and prime it with a drill. Watch the oiling hole in the rocker stand. It should shoot oil about 3 feet high and all over everything. (Ask me how I know) That will tell you if it’s a cam bearing misaligned or plugged up shafts or shims. You’ll have to look up the oil timing and rotate the engine to where it oils in the rotation.