i converted my 88 to carb and i just ran a seperate pump. i ran a holely blue pump wiht braided line although u can go cheaper and use aluminum then you just have to bend it your self. i duno how well your efi pump would work on a carb setup i hope your planning to you a regulator and tunr the pressure way down but that might affect flow. efi pump run high pressure low volume and carb pump run low pressure high volume.i had a hell of a time as well trying to reuse the stock fuelp pump relay to get power to the holley pump and i could not get it to work. im guessing the computer switches on side of that relay from pwoer to ground becasue i coudl not get it to work right so i bought a relay and wired it in myself and just ran the pump to a switch to turn it on or off. carbdford.com has a great write up on converting over to carb and all the wiring thats where i got my info from i hope i could be some help to you.
I have a Holley red I plan on using when I get a sumped tank - however for Temp use i would like to use the eFI PUMP with a return style regulator. I can be done I have seen it used.
I located the green relay under the seat - I tried using the Carb convert writeup but that did not work at all - he was talking about wires in the engine compartment for the fuel pump relay, which I do not have.
I grounded the tan/green stripe wire and ran power to the red/blue stripe wire and got nothing.
Give me some more iedes. I will be using this wiring for the Holley pump as well.