Any body useing a stroked gen 3 hemi engine in there race car?

Not sure I am understanding you, but you said you had to run 7/8 spacers on top of the mounts to get the headers to clear?
I'll look and see if I got some pics of the underneath at the collectors to upload for you. Unfortunately, he's moved just far enough away to where I don't get to see him that often anymore. But when we did that, we shimmed the cab and bed up off the frame nearly an inch with aluminum discs we drilled through to make header clearance. Sort of a short body lift in order to get everything to play together.