This is for my 1966 Skylark with the 464 dressed out for BSA class. OK I got my new gas tank with the EFI pump and my regulator to knock the pressure down for a carb. Can I pump right into the mechanical pump? Or do I need to gut the mechanical pump and pipe through it?
That's how I have mine. My pump is 6-7 psi (no regulator needed) and it pushes to the stock pump, been that way for a almost 15 years and no issues. In the past on my buddies roller cammed engine cut the arm off and made a stock pump pass through. Both examples above are stock appearing fwiw.
Best to push thru a fake pump since you already have a fuel pressure regulator and in-tank electric pump. The stock pump simply becomes another restriction in the system as they are not "free-flowing" like electric pumps, they have valves that open/close varying speed with engine rpms. If the car will see on term street use I would also consider a return system to take some load off the pump......Cliff