Ok this is what the shop said:
We have installed a 2JZ-GTE engine and six speed gearbox from a 1995 Supra. The engine was originally fitted to the car using the original twin turbo sequential ceramic turbochargers. The twin turbochargers were replaced with a single Garrett GT30 475HP turbocharger, a year later. With the modifications we have done the engine produces 450HP.

Now fitted with 2JZ-GTE VVT-i from a 1998 Supra. The engine has a 3.3L stroker kit and turbocharger used is a GT35R 600HP. With this new engine the power is 543 HP at the wheels.
Im inferring this to mean that the original motor was not a 2JZ of sort. Tell me how you read it.

BTW, this came from the website of the shop. Here is the link: http://www.turbofast.com.au/lexus.html