On a street car, I reckon you'd survive with the 1/4 feed to the surge tank if you were running a surge tank. Hell I used to run my Bosch (VL Commodore) external EFI pump through a coil ballast resistor most of the time to keep the pump cool in summer. If it's a race car.. run 5/16ths.

For 5/16th from fuel tank, you are going to need to put in new lines by silver soldering in a new plate where the factory one goes. It's reasonable that you do that. I wouldnt recommend using 1/4 inch return lines at all. I would recommend using 5/16th return line, because at idle almost all of the fuel goes back to the tank. Otherwise if you get some back-pressure, the fuel pressures at the rail may get too high at idle, and will result in over rich and stalling at the lights, which is no good for a street car.

For my sedan:
I have run 5/16th all over.
I have a welded in swirl pot and walbro EFI pump and use a Magna wagon intank pump bracket.

I do get a small fuel leak through the spot welds that hold the swirlpot in the base of the tank, but after a couple of minutes driving it's not noticable.