First investment property help!

Hello,

I need some advice for my first investment property. I have an ex-customer who has a 9 unit apartment building consisting of 9 efficiency apartments, one bed one bath 6-800 sqft.  Rentals right now are $650 some are $700.  But to be safe the total gross  income is approx 5900.00/month. This person is willing to have a second mortgage with him for the 25-% required for an investment property. He is looking for 450k for the building with approx 1000/month for expenses (I.e. elec, heat, etc). The first and second mortgage would be about 3400 a month with taxes. Leaving me with about 1200/month in positive cash flow.  Which in a worst case scenario would still cover me if two of the nine units were not rented. I have personally worked on about 75% off the building updating it (I.e bathrooms, kitchens) units do not need any work. Boiler and water heater are new within five years and the roof was just replaced. So nothing major needs to be done. Any advice or help that anyone could lend would be appreciated.