Person who decided that HDReady should be 1366x768 was a little bit insane.
And personally for me I have even more crazy problem because of that: When I transfer signal through HDMI from 1280x720 notebook to HDReady TV it actually thinks that the signal IS HDReady from 1280x720 and stretches it by that 6% of difference and crops it by 6% and stretches again.
tl;dr As a result I have something around ~1210x660 center part from original 1280x720 signal stretched to 1366x768... Can't find any solution yet.