Greetings from Texas. I'm so glad I found another Z-car with the little 20 under the hood. Mine's In an 83 280zx coupe (I know ya'll down under only got the 2+2).
Better check prices here in the states for that. Plenty of 300ZXT to compare your prices to. I was under the assumption that a 300ZR came with red top RB20DET.