@Tim Swierczek makes a great suggestion! I know Sherman Associates have completed a number of affordable housing projects in Duluth (and were recently navigating another under construction in Lincoln Park that ran into some difficulties). They have utilized a number of financing approaches including: Minnesota Housing Finance Agency Tax Credits, Conventional, Grants through Duluth Economic Development Authority (DEDA), Duluth Housing & Redevelopment Authority (HRA) Assistance.
Sharon Brown with Duluth's Life Safety office is a great resource as well when dealing with blighted properties. She has a ton of resources and could be a great person to connect with to discuss your ideas.
A few other resources that offer funding opportunties for blighted and/or brownfield site renovations are MPCA, Kansas State Technical Assistance to Brownfields, DEED, LISC. You might also connect with Ecolibrium3 and Community Action Duluth to see if they have any upcoming housing projects on which they are looking to source local partners