How to structure a purchase from a Landlord who wants to retire?

[Landyn Smith]

A couple years ago I purchased a duplex from a soon to retire landlord, with the ultimate goal to sell his entire profolio in order to retire. Last year I purchased a SFH in order to BRRR the property in order to have more capital to play with. Its now time to put this deal in action but I'm not entirely sure what the best route is. Heres what im looking at:

His property: 9 duplex

Asking price: 120,000/ per duplex

He is willing to sell off a few at a time but that will takes years for me to set up. My concern is if i wait on this it wont last. My options are clear but unsure on what to do. My SFH- ARV is right at 130k with my loan at 56k. According to my calculations if i pursue a cash out refinance I can take out 47k and use that to put towards the deal. My other option is to sell the property and 1031 the property in order to use roughly 65k. If you guys can lend some advice that would be greatly appreciated.