Fuel cell help

I have a bagged 94 ex. cab chevy and i want to put a fuel cell in my bed.  I have been looking around for one and i found one with a sending unit. (mine is broken) well i noticed that the one it comes with only has about one or 2 wires and the stock one has a few hiring harnesses.  It is my daily so i need a gas gauge. Do you know if i would need to switch out the sending unit to the GM one?  Also i want to install it myself and how would the set up look like?  do you extend your fuel lines or just replace them?  i want to put the fuel cell between the c notch and the tailgate.

thanks for your time