well to start off with you wont have to put electric fuel pump on it because mechanical fuel pump has the same pressure and elec fuel pump and you wont be able to run a fuel pump for an injection system because the pressure is way 2 high your fuel pump will run around 3 psi to 6 psi and so does a elec fuel pump due to the set up (needle and seat and various other internal parts where as efi fuel pump runs 30-60psi wich your carby will just over fill the bowl because to much pressure for needle and seat and will fill bowl up and over flow will just piss out so don't change fuel pump just hook it up a 350 holly will handle it fine i would probly make an expansion chaimber just about carby but yeah if you need any help just ring a place that deals with carbys get a professional view not a novice.