HELP...Best ROI - Should I convert 1 car side of 3 car garage?

[Jenni Moore]

This will be my first big deal purchase....owner financed, 2 bed , 2 ba in the suburban Kansas City, Missouri area. Right now the property is just over 1100 sqft, has a full, but unfinished basement, and 3 (THREE!!) car garage (1 car/1 door and the 2 car/1 door side). I'm looking for advice and suggestions on increasing the ROI. With this being my first property rehab, ideally I'd like to swing the BRRRR method.

I personally think 3 garages is overkill and not sure it would get me any more cash flow as a rental, whereas converting that 1 car side of the garage (it's closest and connected to the rest of the house) into another bedroom puts me in a new ballpark with it being a 3bd/2ba unit. 

I have yet to get bids, as I don't have access to the property just yet - so I have no idea what it would cost to convert the garage. Keep in mind, the property will STILL have a 2-car attached garage.

What are your thoughts and suggestions? Is there anything I should do to the basement that would be a good ROI?

Thanks so much for your time and help! I'm new here and new to all this, but I love this BP community and all the knowledge I've already gained here!