['55 1st series]

I recently bought this 55 1st series and decided to fix her up. I am needing quite a few parts for it. Including new floor panels, hood, bed boards, just to name a few. It has a later year 235 with a 3 speed and I am hoping to put in a 4 speed w/ a floor shifter. Does anyone know if this would just bolt straight up to the 235? Thanks. I'll