Hi Nuno.
Did you use the synchro hardware you bought or not in the end? did you use a resistance for the 2V Input? I really can't find the wiring you used on your post.
Considering that my video exit was highly modified by the former owner (for what purpose? I have no idea), i'm really in need of help on this part

And I need the bezel's size please, will try to have the glass cut this WE. Thanks in advance to all Galaxian owners for this info 
For the PCB to SCART connector : No extra hardware used, no resistance at all ... nothing! Just to wrap wires together.
Let me check in my pictures archive if I can find more pictures I've done at the time.