Rockstro was no fan of the old-system flute (flutes that finger like an 8-key in the lower two octaves but not in the third, eg Siccama, cylinder simple-system flutes etc), but he was kind enough to include in his book suggested third octave fingerings. So, if you have a flute answering to this description, you might find his chart useful. I’ve put it up at:
http://www.mcgee-flutes.com/Pseudo%20Old-System%20Fingerings.htm
Terry