In looking around online for manuscripts which contain Gregory’s oration on Pentecost, I had the fortune of finding two 10th century manuscripts at the British Library: Add. ms. 18231 and Add. ms. 14771. One can view these mss. by visiting http://www.bl.uk/manuscripts and typing the respective numbers into the “Manuscripts” field.
With ms. 18231, not only did I locate an early text (copied in 972, we have a colophon), but I also had the fortune of finding commentary in the margins on our folio (179v.). The scholia is copied from Maximus the Confessor’s Ambigua ad Ioannem. Prior, I had not been able to find a manuscript of this passage online: I had only found the Patrologia Graeca’s text. Clearly I was pleased to find a manuscript with the text, especially one from the tenth century!
The readings from the manuscript differ from the PG, but for the most part they are simple transpositions. This manuscript, both in the main text (Gregory’s oration) and in the commentary contains πρὸς διάκρισιν τῆς βελτίονος instead of πρὸς διάκρισιν τοῦ βελτίονος. Also, the manuscript contains a gap which suggests a lacuna in the first paragraph. This would help make sense of an otherwise rather difficult phrase, though I don’t know what belongs there. I will update the Greek text of my prior post with this commentary, and update the translation a bit too.
I’ve also uploaded the Greek in PDF form, which can be found here.