It depends on what you want to do...
The stock FPR is set at 38-39PSI. If you are just adding the pump so you can supply the correct amount of fuel to the motor (in the upper RPM range) than there probably isn't any need for an adjustable one.
If you are getting a pump one so you can increase the amount of fuel pressure than yes, you will need the adjustable regulator. You should know that you will need a gauge to help set your fuel pressure.