Thinking about putting in an offer...

[Shamus Quirk]

I found a triplex I am interested in buying.  I am going to try to build some rapport with the seller and eventually see if he would agree to some kind of owner financing deal.  He's an older fellow, used to sell real estate from what he says (as an agent) and just doesn't want to deal with the property anymore.  It's a half hour drive or so for him.  It's in a B class town in a B class location.  It is in good condition but could use some updating and current rents are below market.  2 out of the 3 tenants have been there 2+ years and all of them would like to stay but the owner wants to sell so they are currently on a month to month agreement. 

How would you structure an offer that gets the seller to see the value in this deal?

I'm thinking I could keep the current renters, which he might feel good about, plus they have a track record of paying rent with him so thats reassurance I will be able to pay him.  I could also put a down payment down (it would have to be small, maybe $10k for a $379k house.  I also alleviate the need from him to worry about the property maintenance.  I've heard that owner financing helps the seller pay less taxes.  Is that true and if so how does that work?  What am I missing?

Thanks for your input!