Firstly, the design of the sub-dials is anomalous. I have never seen an original 30CH dial with similar sub-dials. The font of the numbers is not right. It looks more reminiscent of UG dials. The 'entirely open' design of the individual hash marks is also not right. By 'entirely open', I mean not connected to a printed circle. Early dials (no winged-hourglass emblem) with large sub-dials like these should have a closed track. Finally, the elongated markings at 3, 6, and 9 in the minute totalizer are not found on this type of 30CH dial.
Secondly, the design of the hour markers is anomalous. While there was arguably more variation in hour marker design than there was in sub-dial design (for a given size), these markers stand out as unusual. One would expect outlines of numbers to be paired with radium. Given that this dial is purportedly "NOS", it seems unlikely that any original radium would have been removed. Additionally, I do not recall ever seeing a 30CH dial with similar, printed triangular hour markings.
Thirdly, the seconds scale and tachymeter scale look very good. Maybe these were done using original equipment.
In short, this dial is anomalous in some significant ways. I am willing to entertain the idea that it was produced by Stern Freres as a spare dial, given the design and execution of the seconds and tahcymeter scales. However, I would struggle to view this dial as 'correct' in a 30CH as it is unlike any original 30CH dial that I have seen in a watch.