New con rod bearings, new timing side bushing, new rings and valve guides, honed the cylinders, assembled with care. Oil pump seemed good, so reinstalled. Tested the switch and it activates at about seven psi. 20/50 conventional oil with Lucas zinc additive for break in. After about 15 miles, the oil pressure light comes on at progressively higher rpms as it gets hotter. Should I be looking at the oil pressure relief valve?