Trading property tax strategy?

[Ian Berg]

I'm purchasing a 2 acre development property from an older lady who has lived there as her primary residence for 20+ years. She wants $1.5M for it which is a fair price. She wants to buy a duplex with part of the proceeds. I have a few newer duplexes that I could trade her. We are thinking I give her a duplex free and clear that's worth $800k and $700k cash. 

Now my question is this: Is there any strategy to help her avoid taxable gains on the trade portion of the sale?

Would it help her tax wise if she carried a note for the $700k or a portion of it rather than taking the money up front?