The bearings you recieved may not be the same bore as what is on the crank. Did the noise start right after the bearing install? Have you owned the engine for its entire life? If not someone may have had the crank and rod journals turned which would require an oversized bearing. This is why plastigauge is a must.

If you are sure it is the lower end, I would think about taking the pan off and inspecting the bearings.