Tax consequences of assignable purchase contract

[Stuart Levine]

I have an assignable purchase contract for two houses as a package. I am sure I can sell one of them for enough to pay off the entire contract, at which point I will own the other house free and clear. My biggest question is when the contract is closed out, Do I report the second house,(valued at about $60,000), as income? Or, do I essentially have a zero basis in the second house, and will report a larger gain when it is,(eventually),sold? 

   I am an experienced investor, renovator, flipper, But have never come across the specific situation. Would really appreciate some tax advice here,Or a referral  to someone who might be able to answer my questions. 

Thanks in advance, Stuart at Zombiehouse restoration