30plus years ago we re-drilled them. Back then, an aftermarket set of axles was $300, almost the same as what they can be bought for today.
We used a lathe to scribe a 4.5" circle on the flange, then drilled and tapped 1/2"X20 holes every 72*.

With the price of axles today, there's no way I'd bother re-drilling. Just the advantage of brake choice is worth the price of the axles. Why stick with expensive, hard to find 10"X1.75" brakes when you can upgrade to cheap and plentiful 10"X2", or larger, brakes.

Do yourself a favor and call Dr Diff.