Good advice, I just called the vendor (who is selling the pump dramatically discounted) and the guy told me it would have to be regulated for my purposes, unless maybe I was running a -8 or 1/2" fuel pickup and line. The restriction of the line at low RPM would would jack the pressure such that at idle and low RPM the needles would never seat. And, complete overkill for my setup generally.

I asked about ratings and he said they pay no attention to them, they go by the manufacturing specifications to see if a given pump could even be in the ball park, then test every pump and tweak to get what they need. He also said they see a huge variance from pump to pump on any given model.

His other additional comment that I found interesting was that with all the electric pump retro fit solutions, hardly anyone does mechanical fuel pumps for hi po streetable anything any more unless they're restricted by a racing class.

Good ol' physics F=AP, or whatever the equivalent equation for fluid is.