I can see why your watchmaker thinks it is a rep bracelet. However, everything except the clasp looks like the real thing to me. The only part I would question is the clasp. Unfortunately, I do not have a 78360 on hand to make a direct comparison, but the pressings & engravings on the clasp do not look quite right to me. Yes, the crown on the outer clasp may have been worn down by repeated polishings. However, if that was the case, I would expect to see at least a little wear on the 2 inside polished sections as well. There is none. But, more importantly, the Rolex insignia that is pressed into your clasp looks different than any of the pressings on any of my gens. Here is a better picture of the pressed-in insignia on your clasp
So either I am wrong about the clasp & the bracelet is 100% gen (likely) or yours is the 2nd bracelet I have seen where someone fit a rep clasp to an otherwise gen bracelet (less likely).