Help me evaluate this lonnie deal

I have been looking for lonnie deals within driving distance from my house in Oklahoma.

I found a dealer who has been renting a 95 16x80 to an elderly couple for $325 a month. They also pay $175 lot rent and have been there 2 years already.

Supposedly his bank asked him to close out this note so he will sell it to me.

If I buy it, I can leave it in the same park and sell to the elderly couple at the same $325 they are renting it at. If they don’t pay I can repo and resell it in the same park.

What is a reasonable price for me to pay for a 95 home I don’t have to move and how much can I charge for it?

He is asking $12K cash - I am thinking of offering $5 - 7K Cash

I could sell it at $15750 over 6 years and the payment is about $325 a month with 14% interest. This would bring me about $23000.

Or I can sell for $17500 over 6 years and its still $325 a month at 10% interest. Total money to me is the same.

How should I attempt to structure this deal? Are my numbers realistic? Should I try to sell it over 7 or 8 years to jack up my total income?

Also where do I get legal paperwork and a contract for the financing I will be offering?