73 340 oil pump

I've run a fine bottle brush through the pressure relief , flat sanded the housings with went sandpaper to reduce clearance and rounded the ports
ya gotta be careful
we also ran blueprinted non HV pumps in stock and heads up classes to reduce pumping losses

biggest change was to run a remote oil pressure relief at the front of the block
with a HP spring at the pump
keeps the oil from going around in circles and reduced foam, air entrapment
you got the correct suggestions above- pull the pan and check your front rod bearings then go from there