3 duplexes, seller financing, curious on terms

[Jacob George Lada]

Hello, I am currently interested in buying 3 duplexes. All are currently rented and bring in 4500 per month gross. Property taxes per seller are 8,000 per year. The owner wants to do seller financing with these terms Asking price: 600,000 but says he is not totally firm. Down payment: 150-175,000 Interest rate: 5-7% Payment: unsure yet but wants a balloon in 5-10 years. So I'm posting looking for advice as I am going to meet with him next week and discuss further in depth about buying the property. I have over 60,000 in savings so also interested in ways of obtaining money for the down payment. Thank you