If WF Norman agrees to modify the finial, the results will not be what was on drawing #3, nor drawing #12, nor as shown in the 1932 image. As in keeping with the evolving history of the octagon finial, the 2016 version will be yet another iteration.
There is a part of me which resists this. This part says: Just paint the damn finial and get it installed this week! Who cares about the damn mounting flange!
However, this part is drowned out by a singing chorus: If you don’t do it right, you will never look at the installed finial with joy. No, you will always think: You should have made that small extra effort when you had the chance.