I've used manual-focus Nikons with 35mm and 28mm lenses for years and have never been troubled with barrel distortion. My favorite wide-angle is a 24mm, haven't found any barrel distortion there either. On occasion I've used a friend's OM-1 with 35 and 28mm lenses too, same story. A Nikon FE might be your best bet. I've used one since the model came out 30 years ago, never failed me. FEs are compact and solid. The price of an FE body is low now, the price of Nikkor lenses relatively somewhat higher.