Purchasing a property with owner financing

[Dean Boyer]

I just want to run this by the biggerpockets community.  I have a chance to purchase a partially finished duplex conversion from a friend that had to move out of the area.  He will carry me for 1 year and 5 months.  During that time he wants me to pay his mortgage of $499.45, which includes insurance and taxes.  I will need to put in about $12-$15,000 to have it fully converted to a duplex that will rent for $1,200 per month.

At the end of the 1 year 5 months, I will purchase the property for $57,000.  He is currently asking $62,000 for it.  Can I just go to the bank and say that I want to refinance it to pay him off?  I think it should be worth at least $75,000 after I rehab.

If I can get it rehabbed in one month, that will let me cash flow about $300/month after withholding vacancy, repairs, cap ex, and paying for water-garbage.  

I am sure I will do this, just not sure how I can handle the refinance at the end of the 1 year 5 month period.