Nathan, I need to warn you! I did the same method on a 1976 FJ55 (using a Ford 460 EFI fuel pump externally). When the fuel level gets low, the fuel starts sloshing, the pump starves, and burns up. EFI pumps are cooled and lubricated by the gasoline flow.
I solved the problem with the method shown below. Use a cheap, low-pressure pump to make constant flow to, and return flow from, the sub-tank (I used a little $20 one from Pep Boys), and put the EFI pump at the lower level of the sub-tank. I made my sub-tank out of an old R12 bottle, but for a later project I used a piece of 4" square tube, 12" long. That worked out fine, also.
The main point is keeping the sub-tank full, so it cannot slosh and aerate the EFI pump. This method proved completely reliable (I built that rig in 1991 and the current owner is still driving it, 18 years later). This also double filters the fuel, when using an old gas tank.
Hope this helps.