Ed,
I don't know if you have all the codes of the PBY's involved, but this article seems to give them, except alas the tie ups....:
http://www.history.navy.mil/download/ww2-5.pdf
Perhaps the names of the mentioned pilots of he 24 May 1941 mission (Byrne in -5 and Rumsey in -9) may help. 52-P-11 was flown by Bill Hardaker.
It appears that -7 was BuNo 2293, -8 BuNo 2292 and -11 BuNo 2291, so can be eliminated.
Regards,
Leendert