Not going to beat on you for asking questions.

Simply put that 3-5 PSI pump will not push fuel to the front of the car when the nitrous is on. Your black pump will do fine for the carbs but the nitrous will be out of fuel a second after the car hooks up.

Y off the line just before the fuel pressure regulator. Run a separate holley regulator for the nitrous system. Buy a Y that has a gauge port on it. In that port install the Hobbs switch ProStDodge was speaking of. Leave the Hobbs switch set at the factory setting 7 psi. This will work fine sense the pump should push at least 12 PSI. When it does not the hobbs switch wired correctly will kill the nitrous.

You really could use more pump. Sense we do not know how much power the car has on motor or how hard it hooks it's hard to say how much pump you really need.

Car launches hard it kills line pressure to the front. The larger the fuel line the more it hurts the line pressure.

How much your car can MPH now in the 1/8 or 1/4 would give us some idea what kind of HP you really have.

I have run nitrous on a lot of cars that was fuel pump limited. I also installed a hobbs switch for security. Customers are always tight when it comes to upgrading the fuel system especially when they do not think they will become hooked on nitrous.

You can PM me some more about how your car runs now and I can tell you if you need more pump or if you can get by. I understand if you may not want to share with the world that information.

Leon