Since it once had an E4OD, the TCM / TECA is probably still there. So should the throttle sensor on the IP, etc. Is the shifter still there?
ZF5 doesn't have a bellhousing; it's the case itself you'd have to re-drill if it was behind a 460. People have put a ZF5 behind in a van, but they never shipped with manuals, so there's no "plug and play" swap. Pedals, floor shifter, and no-shifter column will be your challenges.