Had a look you should be able to find one cheaper than that, most (based on the 2 I have seen) seem to ditch the factory computer and auto, or keep the whole lot factory.
Standard computer is an issue as they need the lexus auto as there too, there are a few places to go for parts Dellows in Aussie do a bellhousing.
I found where I was getting my info for the swap there is a lexus forum only here and has conversions done. I am afraid you need to do a little reading and dont worry about the chev option it has more torque but as a carb won't do angles as well as the lexus and the difference in power torque is not that big when you are only clearing tires, towing a safari out you could notice it a little.
http://www.lextreme.com/
you are looking at buying a computer
Bellhousing
Engine mounts
fuel pump and fuel lines (convert what you have to EFI)
throttle cable
Radiator hoses and radiator
probibly a couple of exhaust sensors for tuning and the computer
some dyno time for tuning (or the software to tune it yourself)
the last two are the only different bits but these give you the fuel economy but you need to do more reading to see if you want to taclke this.