OK, so the plan that is forming in my head so far - I'm impatient (terrible trait that has got me in trouble at least more than once previously with cars) so I will be looking to buy pre built (Bill not making any plans yet but if the cob goes OK then I may be flying out to see you;) ).
I've been studying every GTO pic I can find - the real and the replica and have come to the conclusion that there are two major identifiers to the Z based. The hatchback and the apparant 'stockiness' of the Z compared to the longer looking and more lithe inspiration.
I don't actually think it's so much the wheelbase as the extra depth of the Z body - from messing in photoshop two things really seem to help, getting the car to sit as low as possible, I think speedracers is as low as I've seen although I'm wondering if it's possible to get it to sit lower? On the real article the bottom of the body appears to line up about 3/4 the depth of the wire wheels - is it me or do the replicas seem to sit about half way or higher?
The other, and this really is pandering to optical illusion (and I'd be interested on any thoughts on this), would be a tight graduated shading sprayed to the bottom 1 or 2 inches of the body as it curves under to make the whole car appear 'thinner' and gain an additional bonus of illusion of length to the body. For this to work to maximum advantage the car would really have to sit very low.
Stupid idea? Probably - sounds like me! I'll mock something up in photoshop to see if I can demonstrate what I mean (black cars are excluded obviously *ahem*)
EDIT***
OK, scratch that idea - can't find a decent side view of a replica! Stupid idea anyway, and after even more scrutiny it seems the cabin is shorter on the real thing and it has one hell of a tall upright windscreen. The front wheels are really tucked up in the arches on the real one......hmmm, I think I should just buy one and not worry, lol!
BTW Has anyone ever put a set of knock off Halibrands on one of these?