you dont need a pump. at all. at best you should be at max getting about 12lbs of tank pressure, anything more is too much and overkill. the lid should, if spring tension is correct, pop at about 14-15lbs. a releif valve set to go at 11-12 lbs would keep a consistant pressure to the tank while the motor is running, just drop the one way valve between the pipe and the pressure inlet on the tank. this will do 2 things. number one, it will stop the fuel from flowing into the pressure line causing the dreded left turn bog some experience. 2nd it will keep constant pressure to the tank from the regular souce. no modding needed. the motor and muffler pressure will be more than enough to keep a steady amount of pressure in the tank pushing the fuel to the carb at ALL times. unless you roll over with low fuel ofcourse. so with a releif valve installed in the tank set to 11 or 12 lbs. then you should be all set with consistant pressure to the carb. so you only need to 2 parts, a releive vavle installed into the tank, adn a oneway valve in the pressure line.
Timmahh