The oilfilter had oil in it when i changed it the first time so i think it might be the oil sending unit.
Do not replace the sending unit and start the motor to see if the sending unit suddenly took a dump or you may risk engine damage>
It's more effort but the correct and only way to address the issue at this point is as everyone has suggested,
Pull the distributor and oil pump drive. Install a mechanical gauge and run the pump with a priming rod and drill motor. the correct direction is CW. (clockwise)
