This feature is probably of UK origin.
The character in this story is clearly The Lone Rider (Jim Larrimore), although the name and branding have been removed. Every use of the name "Bret Marshall" appears to have been written in a different lettering style. Some of the text has been Australianised (eg, gaolhouse), suggesting an earlier Australian printing. By the start of the 1970s, US spellings were usually retained in Murray reprints.