The problem with a pre-pump filter is when they get even a little bit dirty they will restrict the fuel flow to the pump and cause a greater vacuum in the fuel system and lower the boiling point of the fuel even lower than modern fuel already is which will then worsen your vapor lock issue. Your best bet is to leave that filter out since it isn't really helping anything anyways. Depending on how much alcohol they put in your fuel on the east coast (it's a huge problem here in Utah) you may end up installing an electric pump right at the fuel tank to push (pressurize and raise the boiling point) the fuel to the motor instead of sucking (apply a vacuum and lower the boiling point) the fuel up to the motor. Hope that helps.
1972 is a stand alone year for the fuel cap and is smaller than the previous years if I remember correctly.
