Many (including the Kent-ish job that came with my C-19) have stubby arms and joints, and do not have convincing tracking geometry.
As for what finish for your Diamond Disc reproducer, while an "oxidized" finish might be "correct", a nickel-plated job will play just as well, if you run across one at an attractive price.
Please post a video of your W-19 in action, if you can !
