I would have also considered layering a wet layer/mount to fill in some of the scrapes when using a LED scanner. There are other side effects but they are a lot

I would have also considered layering a wet layer/mount to fill in some of the scrapes when using a LED scanner. There are other side effects but they are a lot easier to control if you can keep things relatively flat (might require a lot of fluid in some cases but it works wonders). Macro shots are another good way to pull out detail though I find my scanner does a better job in most cases (scanning 2400 to 3200 DPI helps, more is usually overkill for most mediums). The use of a polarizer is a great idea though.