Replacement Engine???

I have a 95 pontiac grand prix that just has the 3.1.....i would like to do something with the car....the body is in spectacular condition...almost looks like its only a few years old....id like to put a different engine in it....just looking for suggestions as to what engines will fit nicely in that car if any??? something to build up...anyone know?? i have availability to a couple of V-techs and a 2JZ ???