The Targa Florio was in TH's catalog for a few years during the early 2000's. There were two versions: the first one with an acrylic crystal and the second one with a sapphire crystal (CX2113).
The later was offered as a "Tribute to Juan Manuel Fangio" numbered, limited edition of 1957 pieces, which happens to be the year when he won his last F1 World Championship. Fangio drove some time in the Targa Florio road race in Italy, supposedly using a Heuer chronograph (at least that was what TH advertising said), and whence the name. Sorry I can't offer more specifics.