How bout you buy a complete GTR, and remove the whole chassis from under the body, unpicking the thousands of spot welds, so youre left with the complete drivetrain inc suspension.
Do the same to the Z and simply slide it under and reweld! Sure it might be different in trackwidth and length (no idea about that), but that can be taken care of with a quick cut and shut and some wheel offset.
Easy!
.....easier than making ATTESA fit into the Z chassis.