I didn't get past the first call before picking mine, as the Realtor I spoke with sounded like a wealth of knowledge mixed with incredible interpersonal and negotiation skills. 

The process starts with the sale of your old property and you must use the services of a qualified intermediary. 

I was under the impression that any borrowed money wouldn’t qualify as “cash only.” 

. + Farmers providing qualifying services to other farmers.

You'd also need to make sure you're able to qualify for a $700,000 loan of course.If that worked and you only ended up with $90,000 in the deal, and you were actually cashflowing $1,000/month, that would give you about a 13% ROI ($12,000 income per year on a $90,000 investment).

@Rob Moran I don't think that's it because I'm in VAAccount Closed I don't think that's it either because it seems like any house with a mortgage qualifies for it

The seller would qualify for installment method of reporting capital gains.

He can initiate a 1031 exchange by selling his property to you, having the exchange documented on the settlement statements and having a qualified intermediary involved to handle the process. 

Is he trying to get a non recourse loan or does he not have enough money to qualify?

Before you rent back to her make sure she is well qualified.