I'm not up to date on your issues so sorry if this is repetitive, but oil sending units can fail and the oil light will stay illuminated. Re no oil to the top end...I'm assuming you know this for certain? If so don't run the bike again.
The oil flows to the top through the outside two crank journals, then through the lower cylinder locating dowels which hold the oil restrictors. If these restrictors are plugged, no oil. The oil pump relief valve and/or spring is in place, oil pump dowel o-rings are in place?