Al, after giving some thought about the directions that came with the Mallory pressure regulator, it states that if you are not using a turbo or some other boost device, to just leave the vacuum port open on the regulator, which may be my best option, as  don't think I have any need to leave it hooked up.  No sudden acceleration of engine anticipated.  I plan on doing the orifices for the EC2 though.  JohnD

Yes, I agree.  I started out with a unit that was not pressure referenced; for the same reason – NA.  But it turned out that Tracy’s EC2 was setup with the assumption of MAP referenced pressure, and I had trouble getting it tuned.  So I replaced the regulator.  This was in the early days of the EC2; maybe that more recent versions will tune fine without MAP reference.

Al