Return fuel system w/ current parts?

This is for my 408.
Electric fuel pump. similar to this http://www.summitracing.com/parts/crt-p4594 BUT its a lift pump out of a dodge diesel (20 psi pump)

And a mechanical pump similar to this http://www.summitracing.com/parts/edl-1720/overview/year/1970/make/plymouth/model/barracuda
My pump is the carter super pump that was sold from MPP.

I want to make a full fuel return system this is how its set up now.

Installed a return bung in the tank, bolted the electric pump on frame next to fuel tank, fuel regulator next to that, fuel return back to tank, and feed line up to mechanical pump, and dead headed at carb.
Regulator set a 5 psi pushing on mechanical pump, carb pressure at 9 psi.

By moving the regulator to the eng compartment, past the carb (how it should be) i worry that 9 psi on the suction side of the mechanical pump will be to much for it.

As i type this, and ponder on how a mechanical pump works, i thing i have already answer my own question. But i will post it up any ways. Would like all your though as i my be way off base!