Or am I just being too particular?
NO !! You're doing a proper re-engineering job. I'm finding the same with the GTO high pipes, attachment points don't line up as well as expected. Never good to install these parts in tension or under stress, something will eventually fail. High pipe conversion was not one of BS's best engineering achievements?, a bit of a lashup really but they do look good
. If you feel she needs the spacers put them in.
To be fair to BS, the high pipes themselves are a work of art, no CAD or computer control in those days, all machine tool presses made by hand and eye. Not surprising the pipes don't line up accurately. Brian.