The Ford fuel pressure specification for the 1966 401--irregardless of whether it is a 2V or 4V engine--is given as 4.5-6.5 PSI.
Was your electric fuel pump activated by a primer switch on the instrument panel? If so, it should be an auto pulse electric unit. They were used on Ford fire apparatus built by both Autolite and AC Delco.
After being involved with Fords and repair parts for over 30 years, I most surely agree with Hotwrech's post: I have YET to see a SINGLE Fawcett electric fuel pump that was worth installing!