First round of testing was very encouraging. Before going to the trouble of pulling the plenum and swapping out the stock fuel regulator I wanted to make sure the rebuilt regulator would control fuel pressure properly and not leak so I hooked it up to a spare set of fuel rails and did some testing with it connected to the car's fuel supply and return lines:
First connected a jumper from the battery + to the fuel pump test connection to run the pumps with out the engine being started.
Tested the stock regulator with and without vacuum being applied
With vacuum 41 psi indicated
Without vacuum 50 psi indicated
Rebuilt regulator with vacuum 42 psi indicated. No problem controlling the full flow of both fuel pumps.
Rebuilt regulator without vacuum 49 psi indicated. No problem controlling the full flow of both fuel pumps.
And best of all, no leaks!
Now on to swapping out the stock regulator and doing some driving tests.