A few toggle design choices

[Brion Toss]

Hello,
As a Coastie once told me, "I reserve the right to be smarter than I used to be, and dumber than I am going to be." So I no longer recommend toggles at both ends of turnbuckles, just the bottoms, for nearly all rigs. Get a turnbuckle body with left-handed strap toggle stud, and thread a Hayn right-handed stud into the top.
T-bars are the most failure-prone terminal, something even Navtec agrees with. You might consider abandoning those T-tangs and installing real ones, especially if you are considering serious voyaging. That way you can go all-Hayn, too.
For the masthead, you can get a built-in toggle, like the one you linked to, from Hayn, or use a separate fitting. The type of toggle you use (forged, double-jaw, or eye-jaw strap toggle) is not as important as the brand. Go with Hayn or Navtec or Schaefer. Specifics like masthead mortise width and terminal type might drive the conformation.
As for strap toggles and crevice corrosion, correlation is not causation; the toggles are not a particular source of the problem. Water is.
Fair leads,
Brion Toss