possible four units on three parcels with owner financing

[Jason K.]

I have a neighbor who owns three parcels of land. There are four units on two of the parcels and one is vacant. Four units and 7 bedrooms total. 

He wants to sell me the properties. Is asking 260k and is willing to finance. 

From tax records I can tell the taxes will be around 4500/ year

The insurance is 1600/ year

Hes talking about a 5% interest rate and is flexible on the other details such as amortization, length of time willing to hold the note, down payment or not and even what I pay per month. 

Any suggestions on how to structure this one? 

Based on local rents I think I can get 25-2700 a month for all four units. 

Ive been trying to come up with an equation that will have me paying around 2k/ mo including P&I Insurance and some maintenance. I plan to manage the prop my self. I will want to refi some time in the near future (3-5 years) so I need to take this into consideration as well.

Any help is appreciated.