I'm not sure that I would like the result, but you could try setting the Latin Gloria to the Old Scottish Chant. It might have a distantly (probably very distant) Ukranian or Byzantine ring to it - especially if you lingered over words, stretched out syllables, and milked every cadence as the Orthodox are wont to do. For better results, find some Byzantine or Russian chant by Rachmaninoff et al. that might be suitable with Latin texts.

Charles of Byzantium might be helpful here.

Have you done any experiments in drawing on the Western tradition of harmonized chant (falsobordone)?

Yes. I'm not shooting for a large-scale falso bordone if that's what you're asking. While I said I wanted to harmonize the chant in a way that resembles Slavic practices, I also want it to be recognizably Latin/Western. I was aware of Paul Jernberg's Mass setting and, while it has some similarity to what I'm aiming for, I think it has a touch more of an Eastern flavor than what I'm after. I guess my question has been answered. Thank you both.

In a similar vein, what about "principle" and/or auxiliary ison(s), I used them back in 2010 for an arrangement of the ICEL Mass. I realize this tradition is more eastern.