I do remember before there were supercharged classes, that supercharged engines were advanced two classes. And before twin cam four valve engines were common, they were advanced one class. I don't remember the other exceptions that you mention. When I started running my Turbo GMC, Blown stock head engines ran in the same class as 12 port GMC engines and flatheads with Ardun heads. XX class. There was a 12 port, a blown flathead, and an Ardun running together with me. I am not sure, but I think it was 81 or 82 when the flat head Fords cried enough to get their own safe space. Some years later the blown classes split my GMC out of XX and into XO/B. So. In the vintage engine classes, specifically XO and XXO number of ports still counts. I don't remember it ever being an issue in the rest of the car classes.