Because of the intake and exhaust sharing the same nut i have always machined the intake and exhaust to the same thinkness. Better chance of not having to chase leaks latter. If the intake and exhaust are different thickness odds are they wont tighten the thinnest piece. Whatever downey says is what i would do he has done it more times than most of us.
Yes, I am sorry for not including that. I had the intake and exhaust machined together. Cost me a lot, but I was tired of chasing the leak. Remflex is good for taking up mismatches, but treat it carefully, it is fragile. I had two damaged in shipping.