[woodcote]

There are two 300SL Coupés on the Scalextric.es and Gaugemaster websites...

   

The #10 from the 1952 Carrera Panamericana (driven by John Fitch and Eugene Geiger) and the #7 private entry to the 1956 Le Mans24 hours (in collectors' edition packaging)...

   

The first Cuban Grand Prix was in 1957 and there was apparently a local 300SL on the entry list, driven by Modesto Bolanos. He did not feature in the results or in event photographs available online. There's a Bang diecast of a 330SL with Trinidad Y Hermano sponsorship and carrying the #10. Whether it's an accurate rendition of the Cuban GP car or a mash-up of the John Fitch Panamericana entry, who knows? There's an interesting family memoir of the race here.

There also a nice write-up of John Fitch at the 1952 Carrera Panamericana here.