I gave the guy some guess work to do really
What he done was left 1mm of bulkhead to locate the crown gear holder and took the cut all the way forward to where the bulkhead gose in an upward direction at 45deg.
The downward cut is 8mm which i'd say is about right as it's the only place you'll be able to add spacing to alter the angle of those upper links should you want to ...........
So in answer to your question YES the downward cut is deeper than is really needed but for a reason !
Might be able to put those measurements on a picture if anyone dosen't understand that