He performed in New York with the Public Theater at Lincoln Center, and with Ensemble Studio Theatre; and in Los Angeles at the Taper, South Coast Repertory and with Padua Playwrights.

In 2007, he wrote and starred in The Backroad Home, a theatrical memoir with his original music, directed and developed by Paul Linke and produced by his wife, Susan Hayden (Ruskin Group Theatre).

Around 1975 or 1976, Allport did a screen test with actress Amy Irving for the parts of Han Solo and Princess Leia, respectively, for the upcoming filming of the 1977 movie Star Wars.

His list of television credits includes appearances on such programs as Midnight Caller, The X-Files, Commander In Chief, ER, Felicity, Mad Men, and Brothers & Sisters.

Allport had written a story about the pleasures of backcountry skiing in the Los Angeles Times in 2004 in which he stated that "any excursion into the mountains requires awareness.