You can, but it isn't necessary. So +1 to above. The only way is to bend them slightly, and if you do this it will last about one ride before the pads are meeting the rim flush again.

Any old stock MAFAC pads still around are unlikely to work properly in 2017. Get yourself some black Koolstop replacement pads and you will be fine. Sand the rim lightly if they squeal, but they probably won't.

If it has the original pads and they are squealing, they are squealing because they are old and dry.