Well, even if we can not get the actual way Latin was spoken (I mean, the accent, and so on) but we have been able to identify the different sounds corresponding to ancient Latin (which could, of course vary because of accents of different speakers) we should be aware that THERE IS NOT an "ecclesiastical" pronounciation. At least, not until the 20th century.
The idea of current italian pronounciation being used throughout the Church for centuries is just A wrong idea. You can find that in times before the rediscovery of the roman pronounciation each person used the pronounciation of their native tongues for Latin, or at least, in many, many cases. I remember Justus Lipsius saying he couldn't understand an English scholar who was talking to him in Latin, thinking that he was speaking in his native tongue; or Erasmus saying that the French were the worst Latin speakers of all (you couldn't just understand their vowels).
This, of course, includes the Church, and for centuries the pronounciation of Latin was, well, that of the tongue of the place. The English pronounced Latin like reading English, so did the French, so did the Spanish people. I have heard old Spanish monks and jesuits who used theSpanish pronounciation and which were told to do so by there teachers long ago.
So this "ecclesiastical" thing is something just made up by the italians who want to impose their pronounciation in the Church and everywhere. I can't find it know, because I'm on y mobile phone and it is 3 in the morning, but there is at least a letter from the Pope in 1912 explaining his wish so the Church uses the Italian pronounciation (I'll edit this soon when I have time).
So perhaps Dante could have used the italian (or Tuscan) pronounciation of his century, but English or Spanish scholars of that time (and well into the 20th century) wouldn't.
The funny thing is that italians are not only trying to change the historical pronounciations of our countries and substituting them with their own, but they have also altered the traditional Latin spelling.
As you know, in ancient times there were only i/u, which were written as I/V and didn't differentiate the vowel sound from consonant one. If you take a look to books of modern times (after the Renaissance) you will find the traditional i/u j/v spelling differentiating both vowel and consonant. Well, since italian dropped the use of J for ortographic reasons, they obviously started writing Latin as they wrote Italian, altering the traditional spelling for Latin into i u/v, droppin the use of J to mark the consonant sound of i, which was customary for centuries (again, take a look on books some centuries old).
So that's why many people write "iustitia" as if they were italians, and not "justitia", (or iustitia, but without any v, following ancient patterns).
Use whatever pronounciation pleases you. English, Spanish, the Reconstructed one, or eventhe Italian one, but be sure there is no "unified" ecclesiastical pronounciation.
“Captivæ Graeciæ lingua in paucorum Eruditorum memoria hodie vivit; laborandum est, ne omnino intereat linguarum pulcherrima” Balbinus, Verisimilia Humaniorum Disciplinarum, XII, 3.
“In omni disciplina infirma est artis præceptio sine summa adsiduitate exercitations” R. ad Herennium, III, 40.