Painting a Master Cylinder

Of the years I have painted master cylinders with a limited degree of success.
Now I need to paint one that has already been painted dingy orange.
I need to go semi gloss black over the orange, I have no idea what paint the orange is but it is nasty.
Anyone have any tips? I think getting it clean will be important, but with what?
Thanks in advance

Just the other day I told my Wife I was going to use a disassembled core master cylinder and do what they do with a cast iron skillet and see what happens.
(Coat it with cooking oil and bake the crap out of it) multiple times probably.