My calculations put it at about $500/month cashflow. My personal goal is for $200/unit, but that is self-managed. So, from that perspective, it is a safe investment. However, I'm showing a 3% Cash on cash return, and a CAP rate under 6%. These numbers are not good at all.
For my numbers, I bumped up your maint/CapX/Turnover to about 7k... which I think is more realistic, but if I use your number it's still a Cash on cash return of only 5%... still not great.
One thing I'd recommend is nailing down the rental rates for this building. I'm working on buying a 4plex that has awesome cashflow, but I've done my own market research and determined that the seller has the rents above market. Maybe he can keep good tenants in at that rate, but I can't count on it, so I'm basing my purchase on lower numbers. If I'm wrong, and it does make that money, I'll be fine with that. So, it seams to me that there is a bit jump between the 1250 rent ant 1650. You need to find out what the market will handle. If the market is 1650.... then this is a great deal. Get the rents of the other units up to 1650 and you'll be 8% Cash on Cash, which is a bare minimum in my opinion. However, if you misjudged, and the 1650 is a fluke and you can only get 1450 for the vacant unit....
So... nail down the rents, and the returns on your money that you need, and go from there. If these are good returns for your area, go for it.