From what I can remember, you need to do the following :
You need to grind down the casing that mounts to the engine, to clear the plate for the water jacket
You need to grind down the top of the starter motor to make it clear the inside of the gearbox
You need to make a custom gearbox mount, as the 20vt one is to short, as you can see, I moved my engine mount over
You will need the later gear linkage
You would need 20vt driveshafts
No idea on the half shaft as I never tried it, but the 16vt kind of fits, but doesn't mount flush on the bracket on the back of the engine.
There maybe other stuff, but I can't remember