Those are bearing surfaces, if you sand them you increase the diameter of cradle and decrease the diameter of journal, plus doing it only on one side will put your Swash plate axis not in line with shaft axis. And by sanding it you cannot keep it round.
It’s your machine and you can do whatever you want, but I don’t think you’ll like the results!
It’s your machine and you can do whatever you want, but I don’t think you’ll like the results!