Other than the obvious, heat and air, plumbing, electrical, roof , etc and the rental history. 

Problem with this property is the Landlord pays all the utilities (heat, hot water, electric). 

Its not uncommon to provide heat and request for the tenant to provide cooling, but your home may sit on the market.

Heat breaks-- you're paying.   

I do not know much about the efficiency of these two different types of heating.

My upstairs unit heat is working great, except in one room (middle bedroom).No heat was coming out of it when I got the property, but my heating guy flushed the system, bled the radiators, replaced the water tank for the furnace, and all was well.

I think your net cash flow is too lean to cover the eventual "expensive turn" due to a bad resident that has a group of unneutered male cats without your knowledge, or the furnace that needs to be replaced due to a cracked heat exchanger that's 11 days outside of warranty. 

The basement and main level have hot water baseboard heating throughout but the upstairs does not have anything for heat.

Tell them you have investors or whatever if you want and you are getting heat to not renew based on these issues maybe. 

Your monthly expense are likely to be much more than $900......did you account for vacancies, turn over repair costs, normal repair costs, capital expenditures (ac/heat units every 15 years or so, not water heaters, roofs, flooring replacements, etc).You can find Loan Amortization calculators online, plug in any term/variables you want.