I'm still playing around with your capture if you don't mind. Since the real resolution of PAL laserdiscs were/are 528 X 576 for 4:3, the real starting resolution of 16:9 slice you're using is 528 x 405. So what I plan on doing is first downsample your disc to 554 x 425 (which is just 105% * 528 x 405 to allow some fudging since it was analogue signal). Do just a little bit of noise reduction, etc and then upsample to 720 x 480 since I'm NTSC. From the samples I've done I think my 480 version looks just as detailed as your 576, but just a little more smoother and natural (no jaggies and less noise).
I got some flack from people when I said I was converting your disc from PAL to NTSC, becase I would loose "detail" since I was going from 720x576 to 720x480, but they failed to realize that we're starting from a source that has less resolution than either. If you go from 405->480 or 405->576 you're going get the same amount of real detail. The quality of the "added detail" from upscaling is dependent on your upscaling algorithms.