Flow it through the regulator with a whip and an .073 jet at 5.5lbs. This is what all of the Induction Solutions, Monte Smith, etc flow tools do. I know, I have one and use it often. You need to have an accurate gauge for this!! At that low of pressure an 1/8 npt gauge will be off by over half a pound according to the kits I've corrected that were set off of one of the small gauges.
Dylan