Oil pump priming

[Big-Foot]

John, the "Bad affect" revolves around the size and pitch of the gears used to drive the oil pump from the camshaft and also the camshaft material.
I am speaking only of Ford Small Blocks here;
Roller Cams are made of steel and require a steel distributor drive gear. The steel gears are not up to the constant high loading of a High Volume or High Pressure pump. This high loading causes a lot of pressure on the gear interface and accelerated wear is the result.
I have seen the gears eat each other up within 30 minutes. Both the camshaft and distributor gear are usually eaten in this process - a few people have gotten lucky with the cams, but very few.
That being said - we run standard volume / standard pressure pumps in all of our small blocks. When the engine is equipped with a remote filter and/or cooler, we use all Aeroquip -12 lines and fittings for the least amount of resistance. Coolers, either Mocal or Setrab - they are both very low impact in terms of resistance.

If I were you, I would pop that oil filter off there and install another just to see if you have a difference in pressure. The pressure reading at the block will be that pressure from the OUTPUT side of the filter.