To clarify. It has nothing to do with displacement or power output up to 200kw.

From the Qld transport website since it refers to you:

High-powered (performance) vehicle restriction

High powered (performance) vehicle restrictions apply for the duration of P1 and P2 licence periods for licence holders under the age of 25 years.

These restrictions also apply to probationary licence holders who return from a disqualification to a P1 or P2 probationary licence, where at the time of the offence they were under 25 years of age. These limits apply for the duration of the probationary period regardless of age.

High powered (performance) vehicles include those with:

- eight or more cylinders
- a turbo-charged or super-charged engine that is not diesel powered
- an engine that has a power output of more than 200 kW as per the manufacturer's specifications
- a rotary engine that has an engine capacity of more than 1146cc as per the manufacturer's specifications
- a modified engine that must be approved under the Transport Operations (Road Use Management — Vehicle Standards and Safety) Regulation 1999, section 30.
This means that you can't legally drive a car with a LA coded mod plate. Read this link for the national legislation on engine modifications.

Section 1.1
MODIFICATIONS NOT REQUIRING CERTIFICATION

• Fitting a replacement new, used or reconditioned engine.
• Fitting a manufacturer’s optional engine for that same model vehicle.
• Fitting replacement original equipment (or equivalent) engine & exhaust components.

In all of the above cases, if the engine is modified, it must be certified under the relevant Approval Code.

Section 1.2
MODIFICATIONS REQUIRING CERTIFICATION UNDER LA APPROVAL CODES

• Fitting equivalent engines (within 20% of original power and engine weight).
• Fitting performance engines.
• Modifying engines and engine components.
Manufacturer optional engines for that same model also means it has to be an Australian delivered model, as only then has the engine passed factory Australian design rule compliance in that vehicle. If didn't come with factory ADR compliance then it will require independent ADR approval. Which is a mod plate.
So the only engines you can stick in an EK without needing a LA coded mod plate are D16's and B16's. And as someone already said, it'd be cheaper to just buy an EK4 than swap in a B16.