A few things I would do, is increase your antialiasing to max. 1200 dpi for resolution is a bit much, stick to 200 or 240 dpi if you like. And the last thing I would try adjusting with caution, is to slightly increase the size of the texture, not too much though that the proportions will become obviously weird. Also, increasing the method to "best" might help?... can't be sure but worth trying out.
You could try rendering a bigger image too, maybe with a width of 1600 or 2000 pixels.