Ok,i could not find NCOP rules for NSW,but if you can and it probably has already been posted.
Have a read of the sections that affect you in your State,they will be the sections that regard engine size,driveline,power to weight and fuel system.
Then check the rules that allow or not allow a "P" plater to drive a car that has an engine that falls in the category.
The other thing as it has been mentioned a few times is that UC did not leave the factory with a V8,it is a bit of bullshit rule
in a way because LH/X did.The only probable difference is that UC had slightly different steering geometry but basically the K frame
was the same as the rest, although legend has it the LCA's were of lighter material along with a few other ("improvements"),and all
that should be needed for V8 into UC is springs and V8 brake booster...along with the normal common sense stuff to make things fit.
The NCOP rules seem at most part just a common sense outline,but because the V8 may come under the.."never came out with it and over power" thing then as already suggested...drop a 6 in it for while.
Even though they might not have come with a blue 3.3 and were an emissions type vehicle,from what i can make out from NCOP is that as long it meets the ADR for emissions with the type of engine fitted there will be no problems regardless of what color it is painted.
"If" going down the blue engine transplant track,it might pay to see or hear or drive or all these things before you buy,they had a varaijet carby that could be trouble or they could be nice.