Thanks for the reply Mark.
The headers on Mark's car are a few years old and made of mild steel. The design is basically the same with the exception of the material( Stainless ) and the flanges are a bit more streamlined and some of the pipes are moved very slightly to give more plug wire routing. Like everything, it is an evolution .
The plugs can all be accessed from the bottom . I typically use a Snap-On chrome swivel spark pug socket which allows some of them to be accessed from the top.
Ron