I'll give you my stock answer. To my way of thinking, it takes the same power to move a certain amount of water whether you're driving the impeller mechanically or electrically, so I would be the last hot rodder on the planet to spend hard earned money on an electric water pump. There are pumps produced by Mezziere that will pump 50-55 gallons per minute and they will do the job, but they are pricey.

I also would not replace a mechanical fuel pump with an electric pump if I were looking to pick up some horsepower.

Leave everything else alone and change the rear gear if you want some real seat-of-the-pants acceleration improvement for the money.