1031 question

[Jules H]

I have an investment property which I'm thinking of selling, its worth approx $900k,  I paid $480k, and owe approx $300k.    I was thinking of doing a 1031 exchange,  but confused whether I need to buy another $900k property to qualify or I can buy a property at $600k instead.   I heard that it should be same or greater value and you need to have a greater mortgage,  but also heard that you can do the exchange and pay taxes on the difference.