Both sides are fed by the oil going to the #4 cam journal, and through the cam when the holes in the cam line up with the holes in the bearing.
Both sides are at the same point in the flow path.

There would have to be a restriction to the feed on the one side to not have equal oiling to the top end.

My thought at this point is....... the #4 cam bearing is toast(as well as maybe a couple more), and may have wadded up some babbitt and stuffed it in the feed holes going to the top...... and the one side is essentially blocked off.