This a 4 unit building constructed in 1916 with roof replaced 3 years back. 2 units has 3 bedroom /1 bath and other 2 unit has 2 bedroom/1 bath + a dinning room.

The good news is that it has a roof, siding and furnace that are in good shape.

The roof of the house looks good but there's a hole in the garage because of a design flaw so we'll have to look at that.

I think you are missing some costs - maintenance new roofs - carpet painting.  

Don't want to sound negative, but I've talked to investors with a large portfolio of houses and they complained to me that profits were eaten up by costs such as replacing roofs, replacing AC's, vandalism or other issues from tenants, evictions, etc.  

I've also done roof, foundation, drywall etc…

I paid 71,500$ for the property, and it has brand new roof, plumbing, electrical, and floors. 

@Christopher McGuire As I look into my crystal ball (OK, it's plastic, but it looks good), here's what I see in your future.1 - You sign an agreement for $400/month, and an option agreement for $25,000 to be paid in 5 years, and accept $3000 up front as an option consideration.2 - Over those 5 years, you will have CAPEX that will cost you around $10,000 (I'm assuming a new roof, furnace, HWH, and at least one more larger expense).  

Anyone have roof leaks after having the attic spray foamed?

You won't have enough money to replace the roof, heating system, windows, carpeting, etc. when they wear out.I believe the insurance, maintenance, water and trash are too low in your figures.