mr Eps, I assume you don't live in melbourne, where you have your car inspected only once and never again for as long as its in your name, unless the police ask you to.
Its a common swap, and done because those engines are readily availble in those countries, unlike the RB (the closest they get to an RB is the RB20E which is an SOHC 2.0L N/A and the RB24S which is an inline 6 carby engine). With this in mind, its easier to do an RB25 or RB26DETT swap in a cef, however the 1JZ and 2JZ swaps are doable.
You'd best be asking on a thai ceffy forum like http://www.cefiro-thailand.com
or
http://rcweb.net/forums/forumdisplay.php?f=31