Negotiating a seller financing deal with a seller I Need help!!

[James Isaacs]

I need help figuring out how to make this deal work. There is a tired landlord looking to sell his portfolio of three properties for 450k. The market value is 510k and they need no work at all. Two of the three units have tenants paying $1650 a month and the other unit is vacant. The owner has agreed to do a seller financing deal. He bought It In 2015 and owes 300k on the property. His monthly payment of principal, interest and taxes is $2890 with a condo fee of 750 for all three units. I’m not sure how much to put down. I’m thinking somewhere between 20k to 40k (I would prefer 20k) but it will be borrowed from another source so that will affect my cost. How do I go about this deal. Do I assume his mortgage and have him seller finance the rest? How do I do this without triggering the due on sale clause? I’m not even completely sure of how I process a transaction like this and what kind of paper work is involved. Please help!