Dating is an estimate from www.ausreprints.com.
First page claims that "This story was based on a true incident that happened in 1849!"
"© S.I. Artists" It is possible, but unlikely that this syndicated story was first published in Australia. Other printings of this story include: Blue Jeans (Editorial Nueva Frontera, 1977 series) #21 (May 1979); and Grandes mitos del oeste (Toutain Editor, 1987 series) #2 (1987).
The GCD calls this story "Jessie Meets Phoebe Arnold" in the index of its original printing, and "Phoebe Arnold" in another printing in Cowboy Western (Charlton, 1954 series) #55 (June 1955).