Good find. I run some 340 manifolds on my R/T heads and had to get adapter cut like mentioned in that post.
Some of what it comes down to is how the heads were cast. When I was putting my motor together, a buddy of mine had a set of Magnum heads on the bench and the material around the port went all the way to the bottom of the head. So I went forward thinking there was plenty of material to seal the manifolds. Then I went to bolt them onto my heads and saw that my ports had just enough material to seal the Magnum exhaust, but not enough for the 340 manifolds. So I had to scrabble and get some adapter cut.
Pretty sure I have posted pictures of the issue and of the adapters on here before. And I still have file, you could get someone like SendCutSend to make a set if you wanted.
