Electric fuel pump for Marcos Ford V6 with 40DFI carb

[Sysygy]

I have a Marcos with a 3L Essex V6 with a 40DFI 5 Weber (no fuel return line), the fuel tank has a return pipe & pick up pipe. I’m thinking of installing an electric fuel pump, but am not exactly sure what I need to do.
The Weber will need about 4psi. I envisage mounting the pump under the tank, feeding it through a pressure reduction valve and returning the excess fuel back to the tank via the return line. Now I don’t think the filler cap is vented so I’m not sure how to vent the system. Can I ‘T’ off the return line and vent up near the filler cap or will I get a boot full of fuel?
An alternative would be a pump with that has an internal bypass when the float shuts off, is there anything out there?

[e42]

Hi, I have a 3L V6 too, can’t help with your question but fyi the Marcos page on Facebook is much more active than here. I registered with the Reliant Scimitar Owners Club (RSSOC) too, as you’ll know they use the same engine and transmission and are a very helpful and active group. I’m currently looking at fitting a 5 speed box , always something to do!