*To what extent are you looking for 'solemnity' rather than 'tradition'?

Tradition is really the point here, now that I think about it. The bind I'm in is that while I can write string quartets, symphonies, or operas with impunity, it would feel somewhat hypocritical of me to write a Mass -- even though in the context of history that's just one more musical genre like the others I mentioned, with its own conventions that make it suitable for particular types of compositional expression.

I should probably just either get over my fear of hypocrisy in this context, or else give up on the direct traditional link and use a text of my own choice, making for a different kind of work, hopefully satisfactory in its own way, that could be perceived as (musically) "related" to the sacred genres of the past.