It offers scores for some of his works, but I don't think his "Mass of the Americas" is listed there yet. Probably the contact page on his website can lead you to get further info.
You might ask the Benedict XVI Institute for Sacred Music and Divine Worship in San Fransisco (https://www.benedictinstitute.org). IIRC, they are the ones who commissioned this work.
There is an interesting review today by Robert Royal at "The Catholic Thing" of La Rocca's Mass (performed at the Basilica in Washington, D.C. in a Tridentine Mass setting).
Watched the entire vid. Beautifully celebrated. Very interesting music. My hat is off to Mr. La Rocca. Truly in the spirit of sacred music and Gregorian undertones with more progressive (the right kind) hints of harmonic nuance. Ave Maria.
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