Help me make sense of this deal.

[Robert Nason]

I have an opportunity to purchase a very large and vacant historic property in a city north of Boston. At the same time of purchase I have an opportunity to sell the first floor retail space as a condo to a restaurant group. I am buying the building for around $800,000 it's four stories and Approximately 16,000 ft.². The purchase price for the first floor condo would be $350,000 as is. The bank would require approximately $200,000 leaving me with $100,000 leaving $50k in unknown costs. I plan on investing an addition $100k to rehab the upper 3 floors into 12 office rentals. I would be forfeiting high rents $5K NNN per month for the retail space forever, but basically getting controlling interest of the building for little to no money down. Time is limited, any suggestion s? Iapproximately 16,000 ft.²