If trans is a 2WD unit, need the shortened output shaft
HERE
Original K-case is slightly stronger because of a 6-bolt torque converter cover, but unless you're going baja, probably not necessary.
Torque converter cover bolt holes may be a clue - I think if 2WD, there may only be 4(?) K-case had 6 I believe.
EDIT: I believe doing the output shaft swap and moving the engine fwd as Tim mentions is the preferred approach.