Insulating inside walls of old house
Although it can' t answer the question for the best solution,
a fast, accurate  and very easy method for insulation simulation is offered on the site www.ubakus.com.
The very important parameters dew points,  moisture and drying time can be seen in seconds, thus disclosing any critical layer combination that could effect the health and damage the walls.
Maybe there is a subsidies program in Illinois - here in Europe some threshold values must be met in order to get public subsidies. And sometimes there is a jungle of different programs, offered by city, county, country - besides tax reduction. Here is a screenshot from another insulation question.