In 1974, McInnes premièred "Concerto on Old English Rounds for Viola," a work he commissioned from William Schuman through a grant from the Ford Foundation.

Jascha Heifetz guided his professional development as a soloist, counseling him to maintain good relationships with the conductor and principal violist of orchestras he performed with.

[8] McInnes played 14 seasons with Camerata Pacifica, a chamber ensemble in Santa Barbara, California.

[10] In 1970, McInnes performed Henri Casadesus's viola concerto, and Paul Hindemith's Trauermusik with the Port Angeles Symphony.

[11] In 1972, he performed Elegy for Solo Viola at a mini festival in honor of Igor Stravinsky at the University of Washington.

[3] In 1971, McInnes received a grant from the Ford Foundation for musicians under age 35, through which he commissioned William Schuman to write "Concerto on Old English Rounds for Viola."

In a review of the New York performance, Harold C. Shonberg described McInnes as a "sensitive musician" "with a gorgeous, mellow sound".

In Classical Music: The Essential Listening Companion, Goodfellow described McInnes's recording as "less prepossessing" than William Lincer's performance of the same piece.

He praised McInnes's "technical finesse" and wrote that the performance of "Fantastic Variations on a Theme From 'Tristan'" "blossom[ed] dramatically."

[21] McInnes performed in many symphony recordings for film soundtracks during the twenty-five years he lived in Los Angeles.

[26] McInnes made arrangements of popular classical music pieces for viola, publishing them through Ovation Press.