Try
www.31stfightergroup.com
They flew Spits before transitioning to Mustangs. This transition happened in Africa or Italy for the 308th FS of the 31st FG though the CO of the 308th kept his Spitfire a long time in Italy. Other squdns. may not have transitioned until later.
I have the book "Mustang Ace" by Lt. Bob Goebel who was a local ace and flew the Mustang "The Flying Dutchman" (HL * N). Excellent book.
P.S. The 31st called themselves the "Thirsty Firsters"