Hello I was wondering if anyone new what was the best PSI to set my Fuel Pressure Regulator at? I think my motor is getting too much fuel it back fires and wants to stall when I punch it very hard start when cold sometimes it even catches fire

I am running a Proform 750 cfm, 4-Barrel Race Series Carburetor and a Holley Blue Electric Fuel Pump & Holley Fuel Pressure Regulator, MSD Pro-Billet Distributor. My motor is a 454BB with a Mild Cam Not sure what cam I have.. I also have a Fuel Pressure Gauge and I am currently at 7PSI.. Truck ran fine before I swaped out the old Fuel Pressure Regulator so my guess would be I didn't set it right since it didn't have a Fuel Pressure Gauge I don't know what it was set at I just went by looks, I tried to match it up as best as I could..
Thanks Pablo