What oil pump to use.

Amazon showed the Melling pump as made in China, might be a knock off for all I know. I doubt I need the high volume pump with standard bearings and clearances, the lifter bores were tight on this block also. My main reason for not using high volume would be to eliminate excess heat build up as I have installed modern air conditioning and I don't want to induce extra heat that is not needed. I don't know how much heat the high volume pump adds but I saw a poster somewhere say that at highway speeds his temps went up 10 degrees, seems like a lot to me. My main concern is valve train oiling through the push rods. I was thinking of using the high pressure spring in a stock pump because of 10 PSI per 1000 RPM rule of thumb. Motor could see above 6000 RPM.