As others have said 1950 is correct for a sandman of early HZ vintage. 6JJ rims are another good indicator. If the body has all sandman indentifiers too then I'd say you've got one, or at least no one could disprove it!

Sandman or not you'd be killing your resale cutting it into a ute, it won't matter how good a job you do, the ute boys won't want a ute stamped panelvan down the track