Before a sensible reply can be given, can you let us know....
What do you want to do with the car.....Street, Race, Rally, Drag race?

How much can you afford.? Not much, a fair bit, or lots?

What mechanical skills do you have? Are you a mechanic, do you have friends who are, or you have never done mechanical work before?

What sort of workshop can you use? Do you have unlimited use of a fully equiped workshop, a two bay home garage, or do you need to work outdoors under a shade tree?

All of these things will affect your ability do perform the job, & while the CA18DET is a good conversion, it may not be possible if you don't have money, the time, a good workshop or the skills.
A good, & cost effective choice is always an A14/15 engine, but even this will require some welding skills, & will also require some wiring harness modifications.

Have a look in the ""Tech Section" on the left side of this screen, as this has many good ideas on what to use. If you can help us with information about yourdelf & your needs, then perhaps we can help you better.