I just got home from my remote work location and I have down loaded the images. Thank you for the offer.
The 18th Fighter Group has potential as the research showed so far. Thank you for your posted references, they are great resouces.
Here is the other information that I found with a reference directly to William Wells that tied him to the 8th Fighter Group.
17 June 1943 – In the last major battle over Guadalcanal, Captain William D. Wells (US 8th Fighter Group) led his flight of P-39 Aircobra fighters into a formation of 30-35 Japanese Aichi Type 99 naval bombers and shot down four of them.
This is the site I sent an email to asking about their source (have not received a response). This is the first mention of a unit that I have found...and why I thought it might be the 18th Fighter Group. There is however an 8th Fighter Group that did operater P-39's at the time...but because the Bellringer article mentions the "13th Army Air Force", we must assume at this point that is correct, which brings us back to the 18th Fighter Group. The Jungle Air Force web site shows the 18th FTG moving to Guadalcanal in April of 1943.
So at this point, I would agree with looking at the 18th Fighter Group. Are there sources that list personnel assigned to the various units...? I have not found any myself.