True Dr Terry. Most rego inspectors down my way don't even look at things like emissions or ADR's when doing the annual inspection on old cars. It seems that as you say, they only really focus on Pre unleaded and Post unleaded.
I've had a Holley, Edelbrock manifold, extractors, etc, etc,.... on my LX Torana for years and they don't even bat an eyelid. It's on Historic rego now, so that doesn't even get checked any more.

I think that as long as your numbers add up there's no real drama. Obviously as per the original topic, a WB chassis will change a few things, but I don't think it would affect rego with regard to ADR27a(b) any more.