Assuming a mortgage from underwater homeowner

[Barshay Graves]

I need some help. I got an offer to purchase someone's home for what they owe on the loan or in other words assume there loan. He say's he owes about $80k (it's a messy divorce situation and he is moving out of state with his new wife, which why he wants out) He is willing to rent the same house for six months for slightly more than current mortgage until he can fully transition out of the home.  The zestimate says it's worth about $117k ( I know not to trust these). But my comps for similar units come near this number and homeowner says his recent appraisal was about $120k

What is the best way to do this can he assign the loan to me? Should I trust this guy? I haven't known him very long?

How do I make this a win-win and protect myself at the same time.

I'm thinking using hard money to buy outright, than refi'ing to lower the mortgage and putting a tenant in it unless I can sell it but buy and hold is more my play...

I'm open to ALL input and expertise...