Keller's earliest editing work includes the Academy Award-nominated films The Five Pennies (1959), Pocketful of Miracles (1961), and Come Blow Your Horn (1963). He earned his first Eddie Award nomination from American Cinema Editors (ACE, of which he was a member) for his work on A Pocketful of Miracles. In addition, he was the editor for the comic films Papa's Delicate Condition (1963, starring Elisha Cook, Jr. and Laurel Goodwin) and For Those Who Think Young (1964, starring James Darren). He also edited the science fiction film Cyborg 2087 (featuring Byron Morrow and Warren Stevens) and the 26th Tarzan franchise film, Tarzan and the Valley of Gold (starring Nancy Kovack and David Opatoshu), both released in 1966.