Feed lines to carb are 7/8"-20 which fit many performance Holley and other. Regulators need to be mounted as close as possible to the carburetor to counter the effects of G-Forces stalling fuel in the lines.
0-100psi Oil Pressure Gauge Fuel Pressure Regulator Gauge Liquid Filled 1/8" NPT
Universal Adjustable Fuel Pressure Regulator Gauge AN6 Pressure Regulator Kit US
Fuel Pressure Regulator, Gauge, Bracket, Holley Carburetor Fuel lines Kit 4150
Fuel Pressure Regulator, Gauge, Bracket, Holley Carburetor Fuel lines Kit USA
Fuel Pressure Regulator, Gauge, Bracket, Holley Carburetor Fuel lines Kit NPT
Fuel Pressure Regulator, Gauge, Bracket, 4500 Holley Dominator Carb Fuel Lines