I would say you would be hard pressed to get it any closer than you have. The car is going to be beautiful and I doubt anyone has done any more research on this model than you have....so the judges won't be able to prove it should be any other way. lol
I agree about the clear coat. It wouldn't be right on a car that is an authentic restoration, and it won't look the same as single stage. Clear will tend to make metallics stand out a bit more and enhances certain colors, making them appear brighter than they were originally.
Great job as always! You should write a restoration book!