According to an October 2 article in the local Star newspaper: "Park Forest has been proceeding with its conversion to SouthCom and is scheduled for operation cutover this week.
SouthCom, the Southern Combined Dispatch and Communication System, is an emergency services network that also serves Matteson, Richton Park and Olympia Fields."
I assume the first place to listen is 470.7625, which is used by those three other communities. That frequency is listed as Cook County Suburb Telecom Network #2 in some sources including Police Call.
Not that it's of any use to a scanner listener, but Matteson and Richton Park also use 470.6125 for their mobile data terminals. The article doesn't mention if Park Forest is adding any MDTs.
A Village of PF article mentioned that the new system is capable of providing PF police and fire with cellphone GPS info for 911 calls. Try Googling "park-forest southcom" for more info.