Well, mileage-wise, it seems the 103 distributor,cap, rotor, and wires will go at least 100k and still look and perform great. The wires are copper strand, and cap and rotor have huge spark areas and are super-beefy. But if they are 20 years old, that might be an argument for replacement, especially the wires.
That being said, I recently replaced the original wires on my '91, at 180k miles, just because I thought I oughta, and hoped it might fix a little warm-start stumble.
The old Berus (I think) looked and checked out just fine. But they were pretty stiff and hard to pull loose from the plugs. I used Bosch replacements, they seem equal or better in quality than the originals.

DG