DOT 5 is required to be purple in color by DOT regulations. This is to provide quick identification. Unfortunatly, the dye can settle out. I had tried it in my '55, turned out it causes leaks in the system unless you use DOT 5 specific rubber components. When I removed the fluid from the system, it was a somewhat greenish color.
If you have any doubt, I'd suggest a complete flush of the system, possibly installing new cups in the cylinders, and start fresh with a known fluid type. Then mark the MC wiht what type is in it for future reference.
