Try this...
Personally, I use a combo of:
-TV Mode
-Smart Motion blur.
To me having both of those on gives it a look similar to the GBA LCD screen. Though it is filtering, it makes the games look more authentic, though 2x or 3x zoom work best rather than fullscreen.
Unfortunately as of late the motion blur with that mode is not working correctly, possibly due to the Catalyst 4.6 drivers.
Try it out.