I can only make some educated guesses and assume none of the fittings have tubes welded on the inside???
Opinion.... The surge tank is supposed to be mounted standing up, the BOTTOM fitting will be for your EFI pump. The others will not be that critical of what goes where once you purge the system of air. Your biggest enemy with a system like this is aerating the fuel with the lines all entering in a close proximity. ANY air in the EFI fuel system is going to cause BIG issues. I have never dealt with bubbles in the fuel entering the EFI pump but I suspect you are going to be able to tell us how it works
This is a band-aid you realize? BUT a very economic way to get things going. I would never rely on this to be the end solution to your fuel delivery system,, but a band-aid to get under way.
The proper way to do it is a custom EFI tank with baffles and an intank pump.
In fact Ricks Tanks makes one just for the 57. Stainless so you will NEVER have to worry about rust, Stock GM type intake pump available at any parts house, an-6 or -8 fittings, (or adapters an- to tube if you prefer) These are WAY over the top tanks but a VERy nice, custom fit and finish piece. I used on in my 67 Camino for the EFI and couldn't be happier.
Ricks tanks for the 57 are available at Jeggs
I know, that $1000 price tag is enough st set you back on your butt. But fuel slosh / loosing power in a hard corner causing a loss of control makes it a sound investment.
My best suggestion is do it right he first time.