We recently picked up a 66 Vette Roadster that had been sitting for 30+ years, there was a sticker on the master cover that said stainless brakes, DOT 5 silicone. After going through receipts it had stainless calipers and silicone fluid put it in when they were rebuilt in the mid 70's.
We checked the fluid and bled the brakes (to ensure it was clean), changed the oil, trans and rear gear lube, then took it out for a ride, no problems, the same dot 5 silicone has been in my father's Woodie Wagon for 20+ years.
If silicone fluid is used to assemble the parts you will have no problems, BUT paint the calipers first as silicone makes it difficult to get paint to stick.
The original paint was used more or less as a preservative between casting and machining.
Here is how they should look.