Abbe Guettee, later Father Vladimir

The journey of this 19th-century French Catholic parish priest and ad hoc historian reminds me of my own a bit. And here's his e-book on the papacy of Rome, one of the reasons he converted to Orthodoxy (along with the poster's helpful comments) - I haven't read it myself yet: More for the to-do list!!

(That page includes links to a number of other briefer essays which look promising.)

A note on the biography page: It says (unclearly) that either then, or now, a Latin priest couldn't normally be received into Orthodoxy as a priest... but I have read elsewhere that that is indeed done at least by some jurisdictions, or has been. FYI.