I don't see how the oil pressure switch would cause this, since that comes into play to keep the pump running after the engine starts. And if the pump was bad (supplying insufficient fuel), it would be more evident as the engine demands more fuel....once the engine is running. I still think it's a priming, or not priming issue. Still have my thinking cap on!!!

 

I feel your pain I am trying to get my 85 Camaro started after replacing the head gaskets.