I have to move 3 of my header tubes to get one on my small block with hedmen headers and a Milidon oil pan. Not a real big project.
Are you sure a little creativity won't work?
I bought mine from Ram Jet Racing and he put high heat material where it is close to the header and then I used 1/8 aluminum plate to keep the diaper against the block. I have very little clearance is a couple of spots.