Whatever you do,do not run a high volume pump with a stock pan.That cost me a 340 bottom end.At high rpm you can drain a stock pans volume quickly.The high pressure relief spring is for engines trhat have large journal clearances,fully grooved bearings or some other reason requiring pressure compensation.
I have a tubed block,solid lifters,2.5thou on the mains,fully grooved bearings and with the high volume mellings and the MP HP spring have cold idle oil pressure at 75psi,warm 55/60..probably a little high .They say on a smallblock that you need 10psi for every 1000 rpm hot.