This could possibly go in the FAQ section, but I don't have any photos on the internals of the motor, just a video to prove it runs.
I took a stock CA20E from the S12, but the R31 Pintara CA20E has thicker side walls I've been told so would be better to use (unconfirmed). You'll also need the head from a JDM CA18DET.
I replaced the stock pistons with ACL (Australian) new standard (non-forged) items that had the 4 valve recesses. I also completely stripped & cleaned the head, block and intake manifold and replaced all of the rings, seals, gaskets, etc.
The head gasket lines up perfectly (same part number between the CA20E & the CA18DET). What doesn't fit are the timing belt & head bolts. The timing path I used was a custom job using an alloy plate to mount the fixed bottom belt pulley, leaving the stock CA18DET top adjustable pulley in place on the head. I had the block re-drilled & re-tapped to suit the CA18DET head bolts but I've ben told VG30 items may fit the stock holes (unconfirmed).
Other items that don't fit are the timing belt covers & the intake manifold bracing. I will have to make up extensions for both of these.
The wiring is a relatively simple conversion, but I left it to someone else to do & I'm still yet to work out what was spliced in for things like the ignition, tacho, water temp, etc.
Note: This engine will never be as strong as a CA18DET as it doesn't have the crank girdle & the cylinder walls are thinner. Even 15psi would probably kill the thing. I'm limiting boost to 5-10psi with the TD05-16G turbo from an Lancer EVO-III.