Undercoating on a restored car to me looks like the restorer is trying not to hide panel replacement so much as all the dents on the bottom side of these cars that they receive over the years of use. Yes, you can hide the plug welds on replacement panels too, but it also hides little dents and dings too. At any rate, it always looks to me that SOMETHING is being hid with undercoating, factory or not.......

I would agree that the overspray and primer look is, well, more. Not many people do this as it is more work, but it sure looks better, and just undercoating in wheel wells and front fender area.

Best of luck!!!!!