From a tax perspective, your brother and you both can't claim the interest benefits. 

I have a little different perspective on this and it comes more from selling in a down market, so it's not necessarily applicable. 

From my perspective, with the information I have, I would keep renting it like Matthew said.

A lot of it depends on what the deal can support as well from a return perspective.

If it is the rent (which I believe and not income), your income from lending perspective is 6500 + .7(1500) = $7550.  

Not worth it from a cash flow perspective, and most of the investors I work with also avoid condos for the same reason! 

From my perspective I would plan for more than 4 months for rehab and sale of the property.

Hard money has me the most scared but if things go well the profit should be approx 700k and the way I look at it, if it goes over time, I will lose money in interest, but with my calculations in the worst case if it would take 6 months to sell id lose 90k in that 6 months out of my profit, and so on...I see (unless we hit a depresssion) as lower risk in that it would take over a few years of not selling before the profit becomes negative (you can see my perspective)  

Jacob, From my perspective I would use a letter.

From a tax planning perspective, you are only allowed to start writing off the home once it is placed into service (once the lease starts).You are also only allowed to write off the depreciation, and any other costs or losses against the earnings from the property.That is, unless they get the real estate professional status, which requires 750 hours a year working in real estate.