Il-2 was used at night for a brief period of time by only two squadrons - one at 35th ShAP VVS KBF (
http://mig3.sovietwarplanes.com/pilots/batievskii/batievskii.htm)
other in 448 ShAP 281 ShAD 14th VA. There were some mentions about one or two more squadrons somewhere in the south, but they all were using Ils from the day-time units as extra load on machines an pilots. So no planes were overpainted for night use due to the fact that it was simply not needed.
Some regiments tried to train to fly Ils at night, for example 141 ShAP, but if i remember correctly, with no success.