Suppose there's a fledgling country just starting out in 1945. While initially aided by the Western Allies and technically allied with them, this country is far from trusted. Because of this, they're only given ex-Luftwaffe planes and other Wehrmacht castoffs rather than state-of-the-art equipment. Ignoring how implausible this might be (there is some basis in reality for this, as the French air assets in Indochina were very much ragtag, including a squadron each of Ju-52s and C-47s converted to be bombers), what modifications and improvements could be implemented to keep such things as the Ju-88 and Bf-109 at least semi-viable into the early '50s?