I'd go with the Holley unit based solely on what I've read on-line.

Regarding upgrading the fuel system. Keeping and using a stock tank with an up-sized return line silver soldered into the stock sending unit is an easy alternative to buying or cutting up and installing an internal fuel pump in an aftermarket tank.

I plumbed my EFI this way. To do this, I run an external pusher pump mounted near the stock tank that feeds a Surge Tank mounted in the engine compartment that free flows at near "0" psi back into the stock tank through an up-sized return line.

The high pressure fuel pump is mounted inside the surge tank, runs through my fuel rails and returns unused fuel back into the surge tank through a bypass regulator.

This system provides air bubble free fuel with the fuel level going down to just above a gallon of fuel in the tank.

I could have just as easily swapped the external pusher pump for an in-tank EFI rated pump that would slip through the stock sending unit opening, but the pusher pump works very well too.

I also run two Permacool water-trap fuel filters that filter down to 2 microns. One mounted under the car before the pusher pump, and one mounted just before the surge tank.