Best Fuel Pump Advice for Newb...

Because 6 seconds at WOT is a very long time, enough to drain the bowls perhaps several times over, and NOT just once. The fact that it made it to the 6 second mark points to restrictions, possibly in the supply side, and after all it's a 72, so the entire supply line could be heavily rusted up inside. Or the tankvent could have failed.Or it's sucking air at the rear jumper. Or the sock is severely gummed up.Or the eccentric has failed.
I just hate throwing parts at a problem and crossing my fingers. I like to know that when I spend 100 or 150 on a customers car, that the problem will be cured. The volume test takes a couple of minutes.
If the supply side turns out OK, then I move to the pressure side. And remembering that debris stuck inside the fitting at the carb , or an incorrectly installed filter there has in the past made a fool of me, that is now my next check.

He wanted the short version, so I complied