Researched this myself a while ago, Mr Bear.
They were a nickel (or similar) shade, as close to chrome as you can get, practically speaking. Just like this
https://noblehouseclassics.nl/wp-content/uploads/2018/12/080-028-0718.jpgIf you want OEM look then go for a silver that 'pops' - though if you google, there are people that have done homebrew remedies with chemicals and electroplating to renew the original finish. So...
a I used some enamel paint which gave the
perfect replication of the original finish... however this has not stood up well and has worn off by about 50% in 5 years on my front ones
b I have opted for a less-accurate visual finish in silver hammerite on the rear calipers, so far not a spec of paint loss 6 months and counting.
c Next time (and when I have some spare calipers) I'll send them in to a sandblaster/powdercoaters and get them to do them. I always try and have a bash myself at any job, I very reluctantly pay anyone to do anything for me, however in this instance the time and money spent in wire brushes, angle grinder electric bill, and paints, versus probably about 」40-50 a pair all-in - and with a result better and longer-lasting than I could ever do, that's what I'll do next time.