I have 3 "good" sets in my parts pile. All of them show shaft and rocker bushing wear to some degree. The bigger problem is the unavailability of rocker arm bushings - if they"re not tight to the shaft oil just runs out the end rather than lubing the shaft and being forced up the rocker to lube the valve and pushrod.
I figured a precision shaft and new brass (not Oillite) bushings, drilled to feed the upper rocker, would be better than another used part that"s already on the path of failure.
I actually thought of rerouting the oil line to feed the shaft directly but that still would leave the clearance problem, would have to flood the upper and starve the cam/mains to get adequate oilling.