If I can, I choose volume over pressure. Both might take the same hp to turn the pump, but I like the extra volume of oil over the higher pressure of possibly less oil. I have seen to many oil pump driveshafts and gears worn out by high pressure oil pumps. A friends 455 Buick twisted the pump shaft right off with 85 psi oil when it was cold. Never heard of any damage from high volume pumps. Heavy oils do the same type of damage to gears and shafts.

1937 Chevrolet Inline-powered Streetrod