Hello!
Compare also to the story of the covering Soviet fighters. It has been discussed earlier at this very forum:
http://forum.12oclockhigh.net/showthread.php?t=4832
So Il-2s were from 35 ShAP (CORRECTION: Chekin was from 566 ShAP which was ARMY not KBF unit!) and fighters from 12 IAP (Tikhomirov one of the pilots). Both units were in Baltic Fleet Air Force ( VVS KBF ).
Kari
PS IIRC FinnAF lost around ten Bf 109s in air-air battles during Vyborg Operation ( = Summer offensive 1944). Of these IIRC again at least two-three ( > 20% ) were shot down by Il-2s. I wouldn't be surprised if the ratio was similar with Luftwaffe in 1944-45.