What has been the experience regarding oil pressure difference when sensed at the oil pump discharge (Smart Craft, ECU feed, etc.) and the seperate dash board oil pressure gage sensor located at the top rear of the engine block above the cam bearing oil galley? The latter is down stream of the oil filter, oil cooler and the internal block oil passage ways and associated plumbing.

During WOT (5800 rpm) runs with oil hot I am reading let us say 55 psi from the Smart Craft gage and 45 psi from the dash gage. Is this typical or not I guess is my main question? Then the next question would be which oil pressure should be used to evaluate whether or not there is adequate oil pressure in the engine?

The basic engine is a Mercruiser 496HO but heavily modified as described in other threads herein.