I did several panelvan to ute conversions back in the 80's and they were quite a bit of work to do..... doing the reverse will be a hell of a lot of work and not an easy job. When it comes to a HJ Sandman a lot of what makes it a Sandman is in the missing roof turret... ie the hoodlining rails and tooth strip. I'd be looking for a good donor shell, even a good windowed shell would be far less work filling in the windows.
Good luck with whatever way you choose to go and as others have said, take pics of the process and post them up..... we love to look at progress pics.
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