Many aftermarket pumps, and regulators are more than capable of supplying your fuel needs. Run a separate regulator for the NOS. So you can tune it independently of your carb. Your fuel pressure at WOT is very important! Any lag in pressure when the NOS is activated can also cause several problems.
You need to flow check your system to see if your pump will supply enough fuel for the motor, and NOS system. My thoughts are the B.G. 220 is marginal at best for what you are spraying right now. The pump, and the regulator is an area that over kill won't hurt! You can spend the money now on the correct pump and regulator. If you run the system LEAN you will wish you had updated your fuel system. I would rather spend the money now, than look at all the motor peices laying in the pan or on the track.
Some people run 2 separate fuel systems for NOS applications. But this can be very taxing on your elec. system. Do you have the propper cam in the motor? You need a more aggressive exh. profile. NOS cams have less exh. overlap, and more exh. duration. Also a NOS controller is very helpfull.
Don't guess, or take anyones word! Flow your system and you will know if it is going to work with out any problems!