No, a stock floor would not change the height of the floor in relation to the cab at all, same amount of head room, but the truck body would rest on the ground, but doing this you need to rebuild the frame rails under the cab atleast so that they are smaller height wise. Its not as difficult as it may sound, just measure 4 times and cut once lol and have good welds.
and well everyone has to start some where, just a few years ago i didnt even know what a welder was lol - mike