How bad do these 3 big mistakes hurt the value of this 340 car?

I agree that it's "restified". It is done so tastefully, but doesn't help the value of the car. What would help is having the #'s matching drivetrain. You can repaint a car as many times as you want to (expensive), but once that #'s matching motor is gone...it's gone for good.
Fully Agree with this. The more original, the more valuable. The farther away the less valuable. But....If you are looking for a fast, fun, cool, Head turner then you can get a sweet duster for $5,000-$10,000 all day long. In this case, I believe the general consensus is that this car is not authentic enough to be worth near the asking price.