In-Tank Electric Fuel Pump

I'm in the process of plumbing the Fuel system on my Magnum swap, I plan on using an in-tank pump on a modified sending unit but I'm having problems squeezing everything in through the existing sending unit hole. I can fit the pump as long as the fuel sender is not attached and vise versa, but can't seem to get both in. I would like to do this without modifying the original tank, has anyone here done an internal electric pump without major modifications to the tank? Or am I just going to have to cut into it and swap in a newer style sump unit?