D-450 headers in early a flange question

Yeah I understood that, but lemmie ask you, other than making them the same size, what would that accomplish? A small port into a big port will have no turbulence. As long as it will seal, send it. It'll be fine.
Correct but when I over lay the Doug’s gasket over the 66’ port the crush area is only like 1/8”. Maybe I’m over thinking because unless I have a muffler failure or a banana blocking my tail pipes there should be no back pressure build up to cause what I invision the “weak link” from blowing out.

when the engine was dyno’ed they used 340 extra long tube headers. No leaks but they did like 10 pulls and it was done. You and I are both old enough to know real world stop and go and torque will create a leak if it can. Murphy’s law or something like that lol!