Well, in hindsight my weekend adventure of installing exhaust headers may not have been much better.
I got to thinking last night that - hmmm, I'm using these old 1961 high performance 390 heads that Keith Craft fully ported and re-worked, and I sure hope these nice, expensive SEC copper gaskets are lining up with ports OK since I'm suddenly remember there are about as many variations of exhaust port configurations as for intake port variations on OEM FE heads. Of course with the motor in the car before I received the gaskets its not easy to see how things are lining up. So, I pull one of the header pipes back off and stick my finger down in there - and crap, there is a 1/4 overhang at the top of the port.
So back to the catalog and there are 3 different exhaust port heigths listed for OEM Ford heads. My first guess was 180 degrees wrong so after a bunch of eyeballing and examination, another order is submitted to JEGS and they won't even ship until the 28th. So, two more weeks wait and meanwhile I have another set of unused copper exhaust gaskets to add to my growing collection hanging on the garage wall.