Deal or walk away?

[Isabel Rao]

Hello all:

I came across a 2 unit multifamily in little village. A C class neighborhood that is actively developing and appreciating. 
it is fully rented out, cash flowing and Coc 10% considering 15k for windows and replacement of hot water tank, 10% vacancy,  15% down, utilities and insurance. 

Now the building is 100 years old, has old ugly siding and has only one egress for the second unit (817 sqft). Also has enclosed porch and updates where no permits were pulled. No current code violations, it is legal 2 unit. 

should I keep or walk away from this deal? 
I am afraid that if I pull permit to renovate sidings or anything, I might trigger city inspection that might cite code violations for other stuff in the building.