Fulgour said:
Based on original research by Robert V. O'Neill,
Strength has always been numbered Eleven.
http://www.tarotpassages.com/old_moonstruck/oneill/8.htm
Justice as Eight was never in question.
I'll leave it to the readers of this post to compare your summary above of O'Neill's findings with the text of O'Neill's articles on Strength and Justice. Onto the substantive issue, I don't see how it can be said that Strength has 'always' been numbered Eleven or that Justice as Eight was never in question. As mentioned in my second post to this thread, the Jacques Viéville Tarot deck (early 17th century), for example, didn't number Strength as Eleven, nor did that deck number Justice as Eight. So much for 'always'.
However, for the sake of discussion, let's assume that such a thing as the Ür-Tarot existed and that its contents were known with some certainty. Let's assume further that such a hypothetical Ür-Tarot had Strength numbered as Eleven and Justice as Eight. Then, the question arises as to whether any variations to tarot can legitimately be made from what is in the Ür-Tarot. To my mind, that would be a question of one's personal view. My personal view on that question (and it's just my view and I sense your view differs from mine), is that tarot is capable of variety from any Ür-Tarot, including variety in trump card numbering, e.g., as in the Viéville deck and as in decks following the Golden Dawn synthesis.