I see a lot of manifolds where the intake and exhaust flanges are not straight across. I have also doubled up the gaskets on the low flanges with good success.
I think that is what the machinist was trying to teach me. I'm sure his reasoning was as long as he was doing everything else it just made sense to true up both (while assembled) to eliminate the hassle of 'making it fit' and being as I was/am a noob messing that up and then burning a valve or something.
I believe he milled it as opposed to using the belt sander, I don't know for sure as I wasn't present for any of that.
I don't know if this is of major or minor import but thought I'd add in my experience for what it's worth... I believe about .02 cents or so.
