No way to tell from a chassis number unless you can find the details of it on the micro fiche from Holden... good luck with that....

It is looking more like a Sandman than not but I would like to see a pic of the body plate to see what the trim and paint codes are.

I would say it probably is a Sandman and if you restored it as one then no one can really say it isn't one as it has all the Sandman identifiers, it would still be worth around $25000 to $30000 fully restored.