I finally found a SOURCE!!! There is a vendor in China selling 4" screens, that are a ***
PERFECT *** match!
Certainly * not * a cheap option, but worth considering as soon as you get a dying screen or already have a dead one!
It accepts CVBS/Composite
AS WELL AS RGB - though I didn´t try this for space reasons. Too many cables add up on the bottom of the motherboard, and you can´t fit it back into the shell, I can prove that, cause I´ve tried to.
The screen beautifully aligns with borders of the screen shell, you get a little black border of the screen itself, so you can line it up perfectly when switched on. It accepts a 9V source, down to 6V (tested), so you can easily solder it directly to the power tap.
Here´s the source:
http://www.aliexpress.com/snapshot/6041400298.html