Hedman tight tubes

Hi all, gotta question about these tight tubes for early A's. I checked these out a few years ago when it was a popular topic which now seems to have dwindled but I'm now in a position where I'm looking at an alternative to crappy 273 manifolds and I need to get this particular thing figured out before the engine gets set in the car. Engine is a 360 /w PS btw. Question I have is that years ago when I was eyeing these headers here was a lot more info about fitting them in an early A and the modifications to do so and now I cannot seem to find hardly anything anymore.

There was a page that covered the modifiying of the drivers side header with pics and good descriptions but it seems to have just disappeared. Searched this site as well and those threads seem to have gone also. I have found a few pics of it and I believe I have the idea down, doesn't seen overly complicated, but want to make sure before I spend the money and start cutting on new headers. I used to see them for sale semi-often on this site as well and they appear to have dried up so I'm curious if that's because its not a popular idea anymore or what. Anyway does anyone still have any of that info or can just give first hand experience at doing the mods and the pitfalls of making it work?