After some thought, i have acquired the 305 instead of the 323.
I went to my AD with my312 on the wrist so i could compare the three watches plus a 45mm ceramic radiomir 292 that was in store to get an overall view!
The 323 is very high like the 312. The 292 seems almost flat compared to them. Another thing i noticed is that a 47mm radiomir is more proportional in size to a 44mm luminor 1950. The lugs and crown protector makes the luminor a much more massive watch when in the same size.
I opted for the 305 because it was the one that felt more diferent from the 312 and 323. The dial of the 323 is very close to the 312 as is the case except for the crown protector imo. The 305 with the larger bezel and unusual dial with the batons was my choice.
I also thought that i should get a next a simple steel 45 radiomir with the 12 3 6 and 9 wich is something that is missing in my current collection! Better than that i think i would have to go to a 47mm SE wich are not easy to find. I also find the 323 too high for a radiomir imo.
And i asked my AD if it is possible to get the 323 strap made for the 312. That strap really makes the watch stand out and is one of the aspects i liked more about the 323.
Another other conclusion i arrived to is that the 47mm of the 305 makes the case more balanced in the width/height ratio when compared to the 312 wich has pretty much the same height. The extra 2mm make the watch sit better on the wrist and the thick accordion like rubber strap also helps in that aspect.
The p9000 movements are really thick. Imo if used on other cases besides the 1950 luminors and radiomirs the end result would not be very good.
Thanks a lot for your important advice.
Will post pics later!