no...no..no offense...but not calling it sector shaft...just sector b/c what you are calling the steering box..iirc, its correct name is steering sector, hence the shaft coming out of it being called ''sector shaft''.
if both ways of tapping box is equal, the endplate and adjustment stud plate, indeed should be easier, because drilling and tapping the top plate can be done on workbench w/o worry of getting chips/shavings in the ''box''.
w/this method being so easy, and you don't have to disassemble the sector to tap and drill to keep metal chips out, why do they tap the box like in picture...when you can do it, w/ the removable plates..w/o complete teardown to avoid metal chips in the box...i thought there must be a reason they tapping the box, instead of the removable plates