It's possible to convert, but it doesn't work for every game and you may have to do it manually. Search for 'ntsc to pal wii save converter' on google.How different is this the to the NTSC version? I would prefer PAL, but have already got 5 hours in on NTSC and, AFAIK there's no converter for the save file.
I tried to use Savegame manager GX with no success.
I created a a PAL save, and extracted it.
Then I extracted the NTSC save.
I replaced the 2 dat files in the PAL save with the ones from the NTSC save.
But it does nothing. If I replace the index file too I got a corrupted save error ...
Tell me if you succeed in converting the NTSC save to PAL.
Thanks.