Both Ireland and Spain can go very far, but going more catholic than the Pope always runs a big risk of the Pope going 'nah, that is beyond the pale'. If you've built your whole political power structure on the catholic religion (rather than Franco's more generic conservatives) that would probably shake your state to the core.This - basically Dev refused requests to have Catholicism become the state religion - either have him go down his road to Damascus of cultural conservatism, have someone else within FF come to power, or have Cosgrave remain in power and continue his rapprochement with the Church - then such an idea could be possible.
I would add that Ireland is unlikely to have a situation in Ireland where women are punished for showing ankle - yes have extremely conservative social and moral values, but I think that even that is a stretch too far. I would say that Francoist Spain is perhaps the closest to such a 'Christian Iran' that is possible in Europe without drastic changes from a PoD.
And the Pope, obviously, has to respond or risk losing the rest of Catholic Europe if the fundamentalist state goes too far.