silent versus sound version

Story has it that Hughes was about to release Hell's Angels as a silent film when the The Jazz Singer with Al Jolson came out. Knowing the public wouldn't be interested in another silent film after the first sound film, he supposedly re-shot some of the film's sequences to include actor dialogue and replaced the love interest with Jean Harlow because the original actress had a strong accent that wouldn't sound English in the film. Is this true? How much of the film was actually re-shot?