Hi
I`m new around here, having just bought a kit of parts that will one day emerge as a 13/60 convertible!, as part of my "retirement" project. My experience of Silicone fluid goes back to 1987, when I rebuilt the brakes on a 2L Mk1 Vittesse. The rebuild included new copper/nickel pipework and ALL the seals, which was the advice I was given. It ran as daily for my wife on short commutes for 3 more year until we sold it. without any issues.
I suspect that said Herald will get the same treatment in the braking dept; Allied to the conversion to MX5 seats, and some updating of the electrical system, New guts for the Radiator and Heater too I suspect. BUT first I have to finish the decorating!!!.
Pete