Hi, thank you for this long post. In fact even if I think that if it may be done in your way, it will be difficult to have the same segment luminosity. May be it's less work to use a microcontroler and redo all the display from the 12 Bcd inputs.
And in both case, its a lot of work just for the "look". So it's not my priority project. I already changed all the 7447 and the 4511 of all my plusgins and it was a big work when the CI was not on carrier.
Thank anyway and if I finally do it during a mong winter evening, I will post the picture on it !