It's about the rocker box > getting the push rods correctly in place ?
Can be a funny job (aka tricky and irritatingly difficult :O) Lot's of info on the forum
ok, so it's just the 2 rocker box covers? Should be fine when taken off and replaced in exact same position, but not so friendly when swapped and turned, I marked them to identify intake - exhaust - top. If for some strange reason any bent stud(s), obviously best to replace. File cover hole(s), a last resort but ok if minimal, imo.