No harm in trying the PRV access as you already have that out, and are aware that ideally the nozzle of the oil can fits inside the orifice left to the extent that the nose of the nozzle might make direct contact with the gallery thus reducing possible leakage of pressure into the over pressure drain... HOWEVER, as I typed earlier even if you loose some oil through leakage to the drain, dependant on which has the least line of resistance to the passage of oil, it seems likely that you may well still prime the pump for it to be able to suck up oil from the sump to then create pressure in the system once the engine is spun over..by whichever method you choose...
Looking forward to reading that all is well...
