The reason the swap have been done in the US is because it is a IS300. It is abit longer that the IS200 and it have engine mount, gearbox mount, driveshaft, gearbox etc already matched for the 2JZ-GTE. Because it runs with a 2JZ-GE from stock.
Making the swap in a IS200 is abit of a job. You would have to make custom mounts for the engine and gearbox, custom driveshaft/spacer, custon exhaust, and i believe the intake has to be modified so it doesnt hit the firewall.
But that is the easy part, the hard part is to get the wiring harness set up with the stock harness.