Bit of a head-scratcher for sure but bottom line is I don't think this is a good idea, and probably neither do you since you're asking.You'd be mixing several systems into one: an electrical chase and a fuel gas exhaust which the chimney technically is whether active or not, and it would probably be considered still active since you have the boiler exhausts in there. 

You must be in a position to withstand the negative cash flow that Michael projects in the event that appreciation is not immediately forthcoming.Good luck

I've exhausted Zillow and the few real estate agents i am working with can't find any deals either.  

Immediately, the Contractor turned on us, the property owners, and says that the resources for this job have been exhausted and that if we want to move forward, he will start billing us and the visit to the city will cost $495.

These are the conservative measures I am taking on all of my analysis and hope that it gives me a decent cushion to be able to withstand any unknowns that occur. 

I would exhaust yourself looking for a deal locally first.

@David HollenbergerIt all depends what level of experience you have with real estate and how much capital you have to withstand the ups and downs of doing a rehab (Trust me, there will be a LOT of ups and downs, more downs sometimes).

Some psychological factors of seller financing vs. refinance: a) seller is exhausted with being landlord and simply does not want to manage tenants/maintenance/hassle of taking out a new loan and therefore still being landlord at the end of the process.

My best advice to you is to exhaust all possible options and areas.

Thanks @Lisa Thoele an exhaust fan sounds like a good idea.