I still have those slots on my '51, and I have a pair of drums from a '53 that still have the slots.
But if you just tighten the shoes all the way with the adjuster and let the anchor pin relax to it's desired position, you probably don't need to mess with the slots.

Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.