There was a huge discussion about this a few years back on this forum. If you wanna read it, try typing "regulator" in the search feature.
I'm guessing you are trying to keep the Holley 1904 from flooding in the wake of having to install a newer fuel pump.
I, myself and many others have tried to use fuel pressure regulators to correct this. All the ones I have tried including the more expensive Holley regulator failed or blew-up in short order.
I ended up placing a bypass filter in the fuel-line ahead of the carb, and ran a new return fuel line back to the gas tank. I also placed an orifice in the fuel-line just ahead of the carburetor. That was years ago, never had a problem since, but it was a lot of work refabricating the existing fuel-line and installing a return line. Also requires welding a short piece of 5/16" tubing to the back of gas tank, but I had a brand new gas tank out of the car, so that wasn't so bad. This was for '55 Ford Courier Sedan Delivery wagon with 223 I-block 6/Ford-O-Matic.