I didn't have in mind "theological" evidence, I meant the Catholic church per se, as an historical entity, along with its hierarchy, sacraments etc. is an historical observable fact that goes back to the first century.
Prove it using non-Roman Catholic (strictly secular, from the period) sources.
Protestant do not deny the Catholic church as a historical entity — so evidence of the historical basis of the sacraments, heirarchy, etc. does not seem to be germane. We are aware they existed for a while ... we think they are wrong.
Protestants typically deny that the Catholic church — particularly since the Protestant reformation — is endowed with any specific exclusivity as the church of Christ. We also deny that any person or entity is endowed with infallibility of any kind. Historical evidence cannot address these objections, so is unlikely to be even remotely persuasive to a Protestant.