Jay, a mechanical gauge would be a real good idea at this point. as far as the sensor you have with the dynon, maybe you should inject air pressure into the sensor to see if it will read. If it does read than you might have air in the oil system on the engine and you will have to get that out. the best way is to inject air pressure into the vent on the tank while cranking the engine(make sure the tank is sealed with the cap on). I generally use a free flowing air blower and limit how much I pull the trigger. Don't run that engine until you know you have oil pressure. you could just leave the sensor out and see if it shoots oil out when you crank the engine, that will tell you real quick if you have pressure or not.

the most important thing is to know your engine is making oil pressure. hope this helps.