You guys are correct. Some pumps seem to be 9psi, some say 7.5-9. The Edelbrock 1403 is 6 max and if you have a reg, set to 5.5.
In trying to figure out why I never need a reg..... I think I always get a pump for a sixties or seventies SBC because they have only one in and one out, in doing so, they are 4.5psi.(M16080) That's what Qjet wants and probably your Edelbrock. Some SBC have a bolt inline with pump rod so as to hold it while installing pump. You probably know this already.