All this critical talk about different engines for the GTO replica, the point is most people build kit car replicas either because they cannot afford the original or want a car that looks good sometimes even better than the original with running costs far below the original, now regarding the Jaguar V12 even if it would fit why would anybody want to put a large heavy complicated and very juicy engine like that in a Z, and we all know you can buy a complete donor car for peanuts, same applies to any Jaguar engine for that matter surely a triple webbered / Dellortoed L series engine would be better, in every respect, I think the only logical and sensible engine to go in a Z as an upgrade to the L series is an American V8, and specifically a Chevy V8, especially as the car in question was built in the US, as for the Lancia V8 it is too underpowered and fragile to make any sense in a Datsun which ultimately is why most people build the GTO replica, because it is based on one of the greatest sports cars of all time, and why of course many think it is sacrilegious to convert a Z in this way, and don't get me started on the 260 or 280Z is a better donor car, cos I think that is a load of nonsense, a Z is a Z and that is it........infact I would rather do the conversion to a 240Z than a 260 / 280 simply cos the 240 has the weaker body panels and would more likely be more knackered and in need of 260/280Z sourced parts to spruce it up, (go think about that all you 240Z snobs)
And apart from bang for the buck, I cannot think of any engine that can sound better than a V8, besides where else can you get a new 6.6 litre engine with 400 reliable old skool (carburettored) horses rearing to go for a grand.