I think it unlikely for them using anything else than the contemporary Greek pronunciation. It was difficult for the peoples of the past to use a non-contemporary pronunciation for any literary/dead-form (of) language, usually possible only if they consciously were keeping antiquated orthography as well (and Romans did that sometimes, like in the declension of "equus", where in nominative singular "ecus" would do pronunciation wise, just like they did quum -> cum after the quom-> quum evolution).
This would have been only possible if Greeks themselves for didactic/recitation purposes kept a form of antiquated pronunciation (just for these purposes), like, for instance, a more melodic accent used to recite Homer than what would the accent be at that time and so on.
So, I don't bring any real data into this discussion, but from my studies of the ancient pronunciations this is how I would (at least) assess the thing.