owner financing and sales of performing notes

[Jill F.]

Finance experts: I would like to ask a seller that (I think) wants too much for a property, to finance the property for me. I think if we did this the seller could get the full amount that he wants in 3 years and I could get better terms than I could get from a bank. The 4 unit property is on the market for $400k with waaaayy below market rents (currently $2900/month total revenue). 

I was thinking If I offered 360, paid 20% down and he financed it for me for 3 years at 5%  with a balloon, he'd walk away with with $401270 and I'd have time to pay down note, get rents up, and hope for better interest rates. Or is there a more attractive way to present this so that he could perhaps sell it as a performing note?

I have excellent credit, own 7 properties in that neighborhood, and have extensive experience managing rentals.