hi lil vulky
i have recently had a problem with fueling too . long story but will tell you what i experienced and what i did. some people will tell you to do all sorts, returen lines etc. up to you but if i was you i would start with the basics and logic then face the problems if and when they come.
i have 2x 600 holleys on top of my supercharger , i was running a mech hi volume elderbrock fuel pump. i change it as i liked the idea of adjusting the carbs to 100% float levels and checking for leaks etc before the engine was running . so im with you on the electic fuel pump , secoundly depending on how old your carb is i had problems with my needle valves not shutting off. even when i put in new ones they are still a bit sticky, after more use they are starting to work alot better , may be a idea to be a rebuild kit and clean it up and change the bits.
i incorrectly bought a bosch electric fuel pump and it sent the fuel pressure up to 12 psi and i soon realised i had bought the wrong pump off of ebay and it was a type that required a retun line and something i didnt need, and i dont think you need .
so as i always had a regulator i rang "real steel " a good american auto shop over here in the uk and they reccomended a holley red top pump . it is the more quieter pump and doesnt require a return pipe .
have fitted it and its great . i had a problem that i couldnt fit it under the car and by the fuel tank. so i had to bleed it to get it pumping as i fitted near the engine bay but on the other side of the inner wing .
i would reccomend you purchace a holley regulator and a holley electric pump. the regulator will come factory set at around 6 psi and is fine for holley carbs. ( most holley carbs will take alot more then 6.5psi as reccomended as their max pressure. most will take up to 8 psi, - speak to any good carb specialist )
house the holley pump as near to the fuel tank as you can but personally i dont like them under the car for obvious reasons. keep away from heat , mine works well under the front wheel arch at the front of the car. but i still need to see how it performs in wot , however i dont feel you will have a fuel delivery issue even if you house it away from the tank. i may have to move it further back, these pump are better at pushing than pulling fuel.
finally if you want to save money and want to work with what you have then simperly put a tee piece at your carb inlet and then say 12" away ( say near the friewall ) place a pressure relase valve set @ 6.1 psi then just a simple rubber return pipe ' the outlet into the TOP of the fuel tank . same as the fuel goes in when you fill up. DO NOT put it under the fuel level as this causes all sorts of problems which will take too long to go into. pressure issues. flow. wrong fuel readings. etc. etc.
however i would prefer the option i have done, depends on what budget you have. both are easy to do but the cheaper option is a return pipe. but you only require it as you have the wrong pump. so i feel you are fixing a problem due to the wrong pump. i would buy the correct pump personally as i dont like the idea of a return pipe. another risk in my opinion. one fuel line is bad enough . oh and a 3/8 fuel line will be fine for what you need. and remember its not fuel pressure you should be hugly concerned about as you mainly need fuel flow @ wot as a lean mixture due to lack of flow is not good . no point having great pressure but no flow when you need it the most.
hope that helps somewhat.
good luck bud