These two ranges work for me:
crt_range0 15600-15800, 49.50-50.20, 3.200, 4.700, 6.000, 0.064, 0.192, 1.056, 0, 0, 192, 288, 448, 576
crt_range1 15600-15800, 59.30-60.50, 1.300, 4.700, 7.000, 0.064, 0.192, 0.898, 0, 0, 192, 248, 448, 480
EDIT : dotclock has been set to 8.0
Combined with some modifications in the TV's service menu they give me full screen games both PAL and NTSC. So no squished video output anywhere.
Few games require adjustments using the sliders. Some do but not many and always minor adaptations.
I still have some vertical overscan.
I can get rid of it all but then there is a blue line and some artifacts in some titles probably because the TV is at its limits somehow.
So now I tweaked it to a degree that it always produces a satisfactory image in every situation. Perfect doesn't exist it seems.
In the mean time I compiled Retroarch and AttractmodePlus. If I use the two ranges in Retroarch it works standalone but if I launch something from AttractmodePlus it crashes. If I don't use the ini it works as expected.
Somehow it freaks out on the resolution change but I still might have some things to try.
It's all but a standard build but all in all very cool stuff.