Dear jmanefiore -
My analysis of your transaction is that you are selling a property with a fair market value of $1,450,000. It has mortgage debt of $400,000 that will be assumed, for a net of $1,050,000.
You are receiving a parcel with a fair market value of $750,000 subject to a mortgage of $100,000 and a note in the amount of $400,000, for a net of $1,050,000 ($750K + $400K - $100K).
Your sales price is $1,450,000 with a gain of $700,000. You are receiving a note of $400,000, net relief of indebtedness of $300,000 ($200K + $200K - $100K) and property with a value of $750,000. The like kind property is only $750K thus $700K will be fully taxable.
You may be able to use the installment method for the portion of the gain that relates to to installment loan.