@Dion - Thanks but, that's not a rule, just a proposal and while I think it's a great proposal, it still doesn't apply to the OP.

The current owner has referred me to someone from whom I sought a proposal.  

However, I've also been running the numbers on a couple of different other scenarios to figure out what the best proposed plan is.

In the over 30 years I have been working in residential construction I have found that your local building department is the first place you will want to consult with and find out if what you are proposing would be legally allowed.

Something seems off but we do not know the terms of this 72k note…….. your potential proposed structure of paying the 53k down , what would that do for him anyway since unless the loan is going to be recalculated to lower the payment, the payment exists ( and I’m assuming its small) which does not explain what the stress is from it.You say the owner is motivated.

When I advertise on craigslist that I am reviewing property proposals and also have a a couple plexes for sale, 90% of my responses are folks looking for more property.  

Make sure that what every you propose doing can carry the debt load & meet your investment goals.

He is actually the one that proposed this situation to me.

I'm merely proposing a solution to them as a way of helping their clients dispose of a financially or physically distressed in a somewhat elegant fashion.Below is the body of the letter. 

He said he would be interested, and asked what I had in mind.So, I proposed a lease option assignment for his asking price of $130,000.