Don't stream at 1080p60 at all, especially only at 1000kbps. Not only is 1000kbps not nearly enough bit rate to make 1080p60 look good, but 1080p60 is extremely difficult for all but the best computers to decode, thanks for Flash being a resource hog. I recommend dropping to 1080p30 or 720p60.
However, to make even that video quality look good, you'll need to increase your bit rate. For both of those options (1080p30 and 720p60) I recommend at least 3000kbps, though I have no idea if your upload rate can support it. Generally you can get some baseline settings from here:
http://obsproject.com/estimator