Shimano 5800 calipers would be a decent upgrade. They can usually be found second hand for less than £40 or buy new for around £25 each.
They won't necessarily work well with levers of that age: cable pull has varied over the years.
It's entirely possible that they'll work fine though.
@Scilly.Suffolk started
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Shimano 5800 calipers would be a decent upgrade. They can usually be found second hand for less than £40 or buy new for around £25 each.