Update!
I had to capture the french PAL laserdisc but the "brand old" Sweetspot (a.k.a. PDI Deluxe) capture card wasn't agree to do that... it worked well with NTSC (albeit the quality was not on par with my old one with a Philips chipset), but with PAL, quality worsen a lot, and it decided to randomly move the picture vertically, to allow the sync codes to be visible, and so cut in half the image (loosing some on top or bottom)... like this:

... I tried the LD output with TV, it was OK; I tried another player, cable, connection, everything the same... I tried another PAL disc, the same... another capture software, reboot the PC, always the same... I tried to deinstall and reinstall softwares, capture card drivers, always the same... I was really discouraged, as I thought to have tried everything... then, flash of genius! As the Sweetspot is based onto bt8x8 chipset, I found another driver for that and BINGO! Now it works, and better than before!!!
So, at the end, I finally captured the french PAL laserdisc; it is 1.33:1, but quite stretched, so it takes, in comparison to NTSC 1.66:1, let's say 85% of the horizontal image and 97% of the vertical one... if one is crazy enough, he could thing to use the PAL image stretched and overlaid to the NTSC one, to increase the source resolution! But don't count on me, though! (^^,)
Now I should only put in sync the french PCM track with the [spoRv] video, and I will release it as a bonus track - that could be remuxed in the final .m2ts, discarding another track, for example the english PCM laserdisc one; but, as my connection is very slow, I'll upload it after the main project seeding will be completed.
@RU.08: there are a lot of problems that I had to solve, to improve the quality of video, and even so, result isn't 100% perfect, but just a very good compromise; so, it will take a lot of time to find out which filters and settings to use to better the quality, and they will be impaired using a compressed version as source... nevertheless, is someone is still interesting in a compressed version of the raw capture...