To answer your question, other than the fuel line, the base car is the same.
So it all depends on how good of job they did.
Did they: change axle, change front and rear springs, add disc brakes(assuming it was a drum brake car), etc? If they did it right, it can be hard to tell a clone from a real one.
They could have just installed a BB and drove on. That's just a hillbilly hack then.....