How to approach a seller for zero downpayment

[James Denon]

I am interested in a 8 family in Springfield Massachusetts. It is an off market deal. The seller is willing to do seller financing with a reasonable rate for 70% LTV.

I would like to offer him this: I will get a loan from a bank for 75% and for him to carry a note for 25%.

So, I would be getting the property for zero downpayment.

Not sure how to approach the topic. I do have great credit and good income to cover the mortgage if anything goes wrong. I have decent track record as an investor. My property manager is great. The property is on the nicer side of town. It should attract good tenants. So, it shouldn't be hard to manage. 

I think he would have to be 2nd lien position on the property and the bank would be have to be first. So, if I default, he is at risk of not getting paid. So, he probably would want me to put down 10-15% to have skin in the game.

How should I approach the topic to get the deal for zero down?