Depends on the country you're in, the version of the CA18 DE (T?) you're after, etc. Personally (although it's a common swap these days and a far better one than a SR20 for a lot of reasons)
it wouldn't be my favorite choice for the ute. As a starting point you will not be able to run a brake booster without some very interesting engineering (can be done but not easily due to the
width of the head and intake manifold) which may be required from an engineering perspective (brakes versus engine/speed potential and all that). Depending where you are a larger master
cylinder and front strut swap may be enough, although it may not be. Just doing this will greatly increase pedal pressure (good if you like having one leg much bigger than the other). It is
legal in most places in Australia, where pre 1977 cars can get away with a lot more radical swaps....
Any gearbox which fits to the CA18 and has enough strength to survive a bit of use means cutting out and replacing the tranny tunnel from something bigger - this generally requires changes to
your heater setup (usually to B210/1600 heater arrangement).
Most engineers would also require a diff swap to stand up to the extra power of the CA18 - even the non turbo version has twice the power of the A12....
Some places require chassis strengthening as well. (Seam welding or bracing).
Few aftermarket fuel injection computers can communicate with the Nissan crank angle sensor(and multi coils), so your options here are limited , increasing costs , or you need to find a good
original one and some way of translating the wiring diagram (good if you're an electrician and it's not in japanese) (and hopefully ensuring all the bits like airflow sensors, oxygen sensors
etc are there.
Most mid 80's on Japanese autos require very specific feeds from their computer and are virtually impossible to use any aftermarket computer.
You will probably need to either change fuel tank to a fuel injected one of a similar size or run a seperate surge tank and twin high pressure fuel pumps. Entire fuel lines will need to be
changed due to the much higher pressure and flow required for injection.
This is just for starters. Think also gearshift lever location, tailshaft length, speedo/tacho connections, radiator changes, engine mount swaps/modifications, crossmember swaps, power
steering/ Air conditioning pumps, etc...
Other suitable options A14/A15 (carb or fuel injected) - easiest possible swap, Ca20/Ca20e (carb or elec ign/fuel inj versions) like above but single cam and very compact - not renowned for
reliability tho

, Z18/Z20/Z22/Z24 (plus turbo versions eg Z18T - fuel injected but can be connected up using fuel only efi computer and electonic dizzy), KA20/KA24 (similar to Z but twin
cam E15/E15T (FWD only but can be fitted with gearbox bellhousing mods) (carb/elec ign or fuel inj turbo). That's just a start of the Nissan ones. Toyota and Mazda (Rotary turbo - Woohoo!)
engines can also fit easily, and even V8's can fit, Buick/GM/Holden V6's etc....
Start with a hot carb/cam exhaust A15 and think about the others while you save your bucks for the job, and the insurance)..... And start checking out some of the guys websites who have how-
to photos.....