Mcqueen, thank you very much for the side by side pictures. Quite useful. Indeed the dial is much larger on the cartel. Maybe not 28mm (I believe even on a 1680 the dial is 26.5mm and case neck is 28.2mm) but there is definitely much more dial real estate on the Cartel.
Indeed I am looking to build one on a Vietnam case, only I might go small crown because I am intrigued by the thin case versions.
At the same time, I also just ordered a small crown thick case cartel like your old one to play around with. I heard early 5512s had a larger 27mm dial so I am hoping to discover an equivalent large dial variation existed in later no-CG models. The idea would be to quickly put together a beater that is also historically correct.