I put a 4ac into my ke70 which originally had a 4kc later on I got defected for worn tyres so I had to get a rwc the guy gave my the rwc but he told me that I had to let vic roads know that there was a different engine, I never did that and I got my defect cleared vic roads still don't know lol
It all depends on how legal you want it I don't know how you will go getting a 4ag through vic roads