BRRR via Seller Financing

[Michael Germano]

I am looking at my first BRRR and I got my first live Motivated Seller offering up Seller finance terms for a 3bed 1 bath SFH in NC. The terms they proposed are as follows...$165k PP, $18k down, Interest only payment at $720 per month with 5% interest with a balloon at 5 years. Currently, has a tenant paying $800 month to month (local rental comps with some rehab (going to say 15k), I could get $1300). What am I missing to understand the numbers for this or what follow-up questions should I be asking to get the best terms possible? Wondering how I would negotiate back. Also does anyone have a seller finance deal calculators they could recommend?