Yes, it's a Holley 12-804 that's rated for 1-4 psi. It comes pre-set from the factory at 2.8 psi, which is just where I wanted it.
I originally thought I wouldn't need/want one, since I was getting 3.5 psi, but after a while I noticed my carb was getting too much fuel and gas was leaking out. The regulator seems to have fixed that.
Plus the pressure had been bouncing up and down due to the pumping of the mechanical pump, and the regulator has smoothed that out.