Here, there is a rule in car judging that says that for a car to be considered a particular make or model, 5 of the 7 major components must be from that model and the others must be period. The 7 components are:
- Chassis
- Engine
- Gearbox
- Front end
- Rear end
- Radiator
- Steering column
It is interesting to note that no part of the body is considered.
In my book, a hot rod usually has a V8 engine, different transmission, steering, front and rear ends at least so too many of he components are "foreign" to that model.
Also, under our system, a modified car cannot be registered as a (say) 1929 Model A if it is modified outside rather stringent constraints. We do not have title for cars so that consideration is irrelevant.