I just had another hunt for that site, Steve, without success. It was six months ago or more that I came across it, in the early days of my computer ownership, and I didn't realise how relevant and rare the material was, and that I should make a note of it.
But the gist of it was that the shape of the ports as they come from the factory is not very good. Also, I'd say, there would be some variance from one bike to another - the finishing of the castings would not be very uniform, I think, and I doubt that the size of the port openings would be specified anyway.
There is relevant material on the net - typing 'pantah, heads, ports, inlet', etc, into Google is a start.
I've never done any porting, but I've seen it done. I think the general idea is to eliminate steps, and to try and make the passage as straight as possible.