I think it's fairly well nailed down by now: the actual watch was auctioned by Antiquorum, the letter of provenance by Schwarzkopf himself mentions a "Seiko 150m quartz diver's watch" (which can only be the 7548), and the catalogue photo shows a US-spec 7548:
In any case, it couldn't have been an SKX009, as the SKX only came to market well after he retired (1996 vs 1991 IIRC).
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