if you buy a front cut with a loom + ECU, then all you would need to do is put in bigger fuel lines, surge tank, a couple of fuel pumps and possibly a battery relocation to get it running in the car.
you'd obviously need a custom exhaust, you might be able to use the stock dump pipe if it doesn't foul on anything, custom tailshaft to suit whatever diff you use, bigger brakes, intercooler pipe work.
Have you considered putting in a 7K-E? loads of torque for a small car, simpler conversion and probably retains more value for the car.