[Plums]

Standard LS1's have the regulator near the fuel pump (in the same plastic cradle in fact) and run fuel out through the fuel filter, then back to the tank via a T-piece in the line.
There is only one fuel line running to the engine bay. This fuel line is high pressure.

If you are going to set-up a return style system, you should have the regulator somewhere in the engine bay, (or up the front somewhere) after your fuel rail of course. This way you only have one high pressure line running the length of the car, (anything after the regulator is low pressure).

Standard LS1 fuel pressure is 59 psi.