What's the POD to get the 390 that much actual range, not paper range?
From the wiki
[Authors Karl Kössler and Günter Ott, in their book Die großen Dessauer: Junkers Ju 89, 90, 290, 390. Die Geschichte einer Flugzeugfamilie] also assert that the Ju 390 V1 prototype was unlikely to have been capable of taking off with the fuel load necessary for a flight of such duration due to strength concerns over its modified structure; it would have required a takeoff weight of 65 tonnes (72 tons), while the maximum takeoff weight during its trials had been 34 tonnes (38 tons). Another explanation for this is that prototypes are never flown at maximum gross weight for their maiden flight until testing can determine the aircraft's handling characteristics. According to Kössler and Ott, the Ju 390 V2 could not have made the US flight either, since they indicate that it was not completed before September/October 1944