Just to add to the info, an email I received from David Birch of enginehistory some years ago.
In 1945 Rolls-Royce changed its mark number system for its transport and civil engines and allocated the 500-range to the single-stage engines and 600 to the two-stage engines. These COMMERCIAL engines included engines sold overseas to airlines and airforces, ie, they were not ordered on a UK government contract. A great number of these engines were Mk.24s, and these were given the commercial mark number 500. Just to confuse you, if an airline had bought ex-RAF Lancastrians and Yorks with Mk.24 engines in them, then they retained that mark number. But if they purchased spare engines from Rolls-Royce, or ordered new Yorks from Avro then they had Mk.500 engines installed. Many second-hand Lancastrains and Yorks had the transport version of the Mk.24 fitted. This was the Mk.T24-2 in military service AND civil service until the new numbering system was initiated. On overhaul the civil ones usually had their mark number changed to 500.
Any Merlin with a mark number of between 500 and 599 is one of the 500-series.There were a number of them, the highest being 549, but most were variants of the Mk.500 with a dash number to denote the operator and the slight installational differences. Most of the 500-series marks were only experimental/development engines. Mk.502 was the only other 500-series mark that entered service.
There were hundreds of 500-series engines, the vast majority installed in Lancastrians and Yorks. The Mk.500 (without a suffix) was for BOAC, Mk.500-2 was for British South American Airways. The 500-29 and 500-45 engines you mention were installed in the Spanish-built Heinkels and Messerschmitts, the dash number indicating a certain build standard appropriate to those aircraft. There were many more. Remember those Argentinian Lincolns? - they had 621-15 engines.
You may find the following of interest
Aircraft Engine Performance Analysis at Rolls-Royce