The Mustang you have done is indeed 343rd FS/55th FG stationed at Wormingford - this scheme with Red, blue and Yellow rudders was enacted perhaps in late October early November 1944. The red mustang was UNIQUE to the 343FS - this one Mustang on Yellow rudder, some on rudder before color code, some not at all. This particular a/c went down with its pilot Ken Mix in a mid air collision with a P-51 of 357FG on December 24, 1944 near Daun.
The 361st had all Yellow spinner and cowl with no rudder colors until the above-mentioned timeframe and of course had 374th (B7), 375th (E2) and 376 (E9) squadron codes.. The cowl decorations ranged from a simple vertical panel ahead of exhaust stacks to the 352nd FG 'sweep' only in yellow instead of blue.
Hope this helps
Bill