DaveW- do you happen to have an oil pressure mechanical gauge screwed in to the oil pressure hole (1/8” pipe thread to the right side of the distributor)?
This will let you know you have sufficient oil pressure. Remember how the oiling system works. The parts have to line up with a hole to pressurize the left and right (separately) bank. Hand turning over may not allways allow sufficient fill time. You may not have an issue but I understand your concern.