What's your question with the hour subdial? Looks good to me.
Afaik, when the caliber is the 287 (the most used on these Aero) the numerals on the hour subdial are a little smaller than the numerals on the other subdials. In the smaller calibers (281, 283 or 285) the size of the numerals is similar in all the subdials (except the memento subdial where the numerals are thicker).
You can see both examples in sala but the significant majority show regular flat top 3s in bottom three registers and the rounded 3 in the upper register only.
I think the dial looks good and is original but just to have some extra point of reference, if you know it, could you please tell us the serial numbers? My theory is that very very early Aero-Compaxes have the round top 3 both in the memento and hour subdials, whereas slightly later ones have the 3 with round top only in the memento subdial and flat top 3 in the hour subdial.
Also, on super early ones there is no "swiss" written at 6 o'clock, where as even slightly later ones have it.
I am not able to 100% prove it but that is my hypothesis.
I own a steel Aero Compax with the lowest serial number I have ever seen on an Aero Compax (752xxx, same as the very first and earliest one shown on the Sala's book) and it has no "swiss" and round 3 also in the hour subdial.
The minute and hour hands should be blued stick hands, that compliment the dial much better than the sword lumed ones also because the hour markers are only painted and in stick-like shape as well
yes with that serial number is one of the very very first ones.
Considering that the hands are surely not there originally, the hypothesis of the service dial is plausible. Still I would consider it an original UG dial and in great conditions hence overall I really like that watch! If you find the stick hands it will also look much better IMHO