You hit the nail right on the head...It will idle fine as soon as he tries to drive it and being a double pumper doesnt take long to empty the bowls to a point to make it run shatty because the pump wont keep up where its mounted. (Its having to pull gas from tank and push to carb.)

Till you get another pump, move it close to the tank as you can get it and it MAY get you buy for a bit till you can upgrade HTH
Like I said you have a damn good start to a nice car!! Cant complain for the price either