Need confusing deal advice

[Drake Espenlaub]

I am a broker and have a client who listed his paid off investment property with me. His family is wanting to purchase a nicer home and in effort to get money down he is selling a ran down rental. He has someone contacting him to purchase the home for $700 a month for 3 years. The home is currently rented for $550. 

I offered my seller $10,000 cash to assume the risk of the deal in which he is likely going to take.

I know we shouldn’t assume..but I am talking with the potential contract buyer who sounds stand up. So ASSUMING he can come up with $1,500 down, and the $700 a month I would be willing to sell it to him for 25k. 

This would be my first wholesale/contract deal 

Best way to work this deal? Buy it, lawyer write up a contract sale document, give new buyer equitable title and move on?