If you're running a carb, or multiple carbs my first choice would be to switch to a high volume mechanical pump, like one from Holley or Carter, made for performance engines. Summit sells several - http://www.summitracing.com/search/b...tOrder=Default The mechanical pumps are tried & true, and provided you're not running EFI where you need high pressure, you're not relying on an electric drive that will fail at some point in time.

If you're set on running the electric then you need to follow the manufacturers recommendations for mounting it as close to the tank as possible, and below the tank to the extent possible. These pumps are made to push, and if you make them lift the fuel they will fail much quicker. You can use your existing tank, but it depends on your regulator if you have to have a return line or not. There are two types, one bypasses back to the tank, and the other simply backs the pump up on it's curve and chokes flow. There are different schools of thought on filters. Most instructions that I have seen say to install the provided filter downstream of the pump, but many people believe that having the filter ahead of the pump protects the pump from debris in the tank. This is true, but if that inlet filter plugs, or partly plugs you are going to starve the pump which is equivalent to mounting it above the tank and making it suck fuel - you'll burn up your pump, often in short order. Bottom line, you need a clean tank to run an electric pump. Mechanical pumps are much, much more forgiving, and will just keep on pumping until the diaphragm ruptures.