340 motor pumping excess oil on right side

Are you saying the valve cover let's oil stack up (for lack of a better term) along the rail by the number 8 cylinder??
Yes, the valve cover mounting flange is thick, and the valve cover wall is on the exterior of the flanges. So it can collect there, as well as that area of the head. AND the breather baffle isn't the best design. The angled ends don't block much at all.