First potential portfolio/commercial deal questions

[Arian Mustafa]

A deal has come across my desk that I am hoping to get some advice from the BP community. Older gentleman who has for decades owned and accumulated class A properties, all in the same town north of Boston. I have lived in this town in the past and am very familiar with it. Excellent area, great schools, and desirable for renters who are willing to pay more to live in an upper class zip code. 
This owner and his family have accumulated 60 units, a total of 14 properties. He is looking at around $16-18mil price point but is open to reasonable offers. 100% rented, all rents up to date, and pretty close to market rents, with some room for increases. 

So far I have tried to stay in my sweet spot of 3-fam and 4-fam properties.  However for something like this deal to come around, this type of portfolio does not come around often. So naturally I want to at least explore the idea and see what I would need to do to make it work. 
Main issue obviously for me is that I do not have the 25/30% down payment for a commercial loan. Thats not happening. For anyone who has gone through this path before or has knowledge, I would love to hear some ideas of how to approach this seller.  Would love to pitch this seller a seller financing option. I am willing and open to listening to any and all suggestions. 

Also how does one analyze this type of portfolio?  Without knowing the property condition for each of these buildings, how do you go about analyzing and seeing what a realistic purchase offer should be based on current rent rolls, rent ledger, location, condition, potential renovations needed, and potential rent increases.

Thanks in advance all!!!