Switched out my Casino Royale Seamaster with my brother for his Speedy Pro today and put the strap I had for the Seamaster on it. I also bought the Speedy Racing rubber bracelet and another deployant clasp for my FOIS. I didn’t like the 19mm taper to 16mm strap it came with since the 16 felt small.
It's the nylon herringbone strap that came with the Railmaster. Got it from my OB, $250 for the strap and $50 for the buckle. Here are the part numbers: CWZ007427 medium CWZ009616 short
Ample time to play with strap and bracelet combos; there’s good reasons for the 1039 to be as desired as it is...