Was put off by other owners experience saying specialized headsets were a minefield, and the best thing to do was get a specialized dealer to tell you which one would fit.
It wasn't even complicated, I plum forget what headset I have order for a customer's Specialized who have similar headset, but needless to said it was a fairly common one (either FSA or Cane Creek).
If it look like this, then that can be easily removed and replaced with a cartridge;
It did fit, you just need to removed the old headset shell from the frame in order to fit a modern cartridge bearing in.