Help me structure a deal

[Qulia Brunson]

Good Day fellow BPers,

My expired listing marketing is starting to pay off. I met with a couple yesterday who received my post cards from my expired listing campaign. The house is a family home that has been in the family since it was built in 1908. I say that to say it has alot of love in it and not much work is needed besides from an eyeball inspection. So here are the numbers I'm working with:

3bed/2ba 

1900+ Sq ft

Tax value $72500

Asking price $50000

Market rent $700-$800

Owner is willing to finance but wants original asking price from listing which was $57,100. I'm looking to add this to my rental portfolio but this is the first time a homeowner has been willing to finance. 

 So my question is what would you offer this owner,  for those experienced in owner financing? Also, please advise if any additional clauses should be included in the contract. I'm trying to make this deal a win for all parties involved.