I'm here, Cees, lurking in the background but I don't have anything substantial to add. The swedes were very efficient when it came to scrapping military equipment during those days and today, they are scrapping the whole defence - men, women and equipment.
If there was a "hidden source" of swedish built DB 605, then I believe it would have been found by now but never say never. The build quality was better for the swedish built ones than for the original batch(es) that were delivered from Germany. As far as I know, the single engined SAAB 21 never flew with a german built engine and the twin engined SAAB 18 was to be fitted with at least one swedish built engine.
Anyway, if someone was to find one and fit the engine to a genuine BF 109 ......

...... what would the purists say?
Christer