Hi @Jim Frye,
I really like your analysis spreadsheet! You seem to be very thorough in your expenses and accounting for the ones you should. It's often the downfall of new investors to conveniently "forget" about certain expenses like vacancy or cap ex. to justify their purchase, so I think you're taking the right approach in being conservative with your numbers.
I just have a few comments. First, as @Christopher M. alluded to, do not trust Zestimates when estimating rent, appreciation, or house value. It can be a slippery slope of assumptions that end up burning you if you can't prove they're right. I find that in general, Zestimates are usually within about +/- 30% of the actual numbers so it may be held as a general guideline for *about* how much a house may be worth or rent for, but take it with a grain of salt for sure.
Oak Park is in a good spot right now in terms of appreciation for the area, but I personally tend to be cautious about assuming any more than 3% annual appreciation. 3% has been the overall average appreciation across many decades, and any appreciation that ends up above and beyond what I assume is icing on the cake. Lowering the rate of appreciation from 4.4% to 3% decreases the value in 5 years by $10,000 from what you have in the spreadsheet, so just be aware.
Your cash flow would be less than $100/mo starting out. This seems a little tight for me. One major expense that comes up costing you $5k and there goes your cash flow for the next 4 years! And how do you know there will be absolutely nothing you need to do to the house to prep it for rent? Just a little too tight in the cash flow department for Oak Park in my opinion. Perhaps try aiming for a house that will get you more than 1% monthly rent-to-purchase price so the cash flow can improve to safer levels, to protect yourself against any surprises.
I hope this helps! Best of luck!