I lived in Jackson Heights from when I was born in 1950 to the 1970's. During those early years there was a large Jewish community although I wouldn't characterize it as German-Jewish. Most of the people I knew were second generation Jews who families left the Lower East Side to settle in neighborhoods in Brooklyn, Bronx, and in my father's case Rockaway. Jackson Heights in 1950's was a temporary stopping point for many of these families as they moved on to the suburbs of Long Island and New Jersey. In the 1950's almost all my friends were Jewish but by the time I went to Junior High School (13 years old) they were almost all gone. There were 2 synagogues in my neighborhood: one was Conservative and the other was an Orthodox Young Israel.
I'm not sure if any of this helps. Please contact me if you need any more information.
Researching: Tishman, Yurik, Becker/Packer, Gordon, Finkelstein, Herzfeld, Horneburg, Nierenburg, Gamarnick, Smolin/Smolinsky, Weinstein, Brilliant, Mellon/Millonchick