We have an 8-unit apartment building that has 4 furnished MTR units in it.

I had to go to zoning and spend thousands to get it legalized.Your situation seems as if it is zoned as a single family home, and it was split into 2 apartments with no building permits.He's selling the property because he has the wrong zoning, and is finding a bank or an investor who over looks the problems that will arise once they close.With the way things are with insurance, I wouldn't be surprised if your insurance company will not insure for two unitsgood luckGino

It is better for us to move the tenants out whenever we take over a building that has rents that are way under market.

Do this for a year or two and build up more cash, and then do it again. 

I was part-time for 6 months while working a government job (no cell phones allowed in the building). 2 rentals closed in 6 months, no sales.

I've begun keeping receipts on upgrades, fees, etc... to be prepared for tax time. 

I noticed your link was actually to the previous Chicago Building Code "13B". 

Both are older homes, the 3/3 was renovated in the 80s.2/1 home is prime candidate for a tandem house out back or teardown and convert to Rowhome zoning, (properties were recently rezoned just across the alley tandem homes, ADU already zoned ok) 3/3 is newer, on a double lot, but my thinking is that I could hold these for a while, go through the rezoning process and sell both if/when the neighborhood continues to get hot enough for more density building, possibly work with a contractor friend of mine to get going in this direction, or try to do construction of tandem home behind 2/2 and then adu behind 3/3 home.Are there any resources for spreadsheets or analysis specifically in this realm/that I could show my financiers to calculate the projections on this?

I have acquired my experience from working on my personal live-in-flips and building ADUs, as an owner builder and self-performing most of the work.

The property is rented by DCFS ( department of child and family services) a government tenant and are occupying the building for last 30 years and have no plans of relocating.