Okay, this might get a bit confusing, but let me try to sort out some of the history for you.Some of this info you might already know, but at least other board members can follow our discussion.
The 54th FS was activated in 1940 as the 54th Pursuit Squadron.In early 1942 it was redesignated the 54th Fighter Squadron.
During the war, squadron assignments changed.Especially early on, squadrons were assigned to groups, commands, etc as needed. In 1941 the 54th PS was indeed attached to the 55th Pursuit Group.
It appears from my histories here at home that in May 1942, two things happened: the 55th Pursuit Group was redesignated the 55th Fighter Group, and the 54th Fighter Squadron was detatched from the Group.
It also appears that the 55th Fighter Group, without the 54th Fighter Squadron, continued to train in Washington state before being sent to England in 1943.
Meanwhile, the 54th Fighter Squadron, unattached to a higher group, remained on station at Elmendorf Field, Alaska, until it was attached to the newly formed 343rd Fighter Group in September 1942.
In June 1942 the Japanese attacked and occupied 2 islands on the Aleutian chain (Attu and Kiska).The 54th Fighter Squadron, the 343th Fighter Group, and other elements of the 11th Air Force frequently attacked the Japanese positions there, as well as conducting scouting missions in the Aleutian area.
Regarding contacting other vets from the campaign, I'd see if there's a 343rd FG association, or even an 11th Air Force group.
You didn't mention if the a/c was lost on a combat mission or lost as a result of accident.If it was an accident, there might be an Aircraft Accident Report on file.Check with the Air Force Historical Research Agency.