Do i need a proportioning Valve?

What application is the master cylinder for? Drum brakes require a residual pressure valve to hold a slight pressure and keep the wheel cylinder seal cups expanded, discs do not require this as the residual pressure would cause the brakes to drag slightly.

As you have now 4 wheel discs you will require an aftermarket master specifically for 4 wheel disc brakes, and it should come with instructions regarding which is the front, and which is the back.