My original motor, gearbox and diff are all long gone. Well before I ever bought the van. The numbers match though, so to me, bringing it back to 'original' will only mean 308 M21 and 3.36 diff. It might be LSD and I might go discs. Also I'll keep it Mandarin Red and Keep the black interior. Thats important to me. If I saw a Sandman advertised and nothing matched, paint, motor, gearbox (specifically auto to manual or vice versa) it wouldn't appeal to me at all.
Sandmans are very popular currently. Any panelvan is over priced and called a Sandman regardless. If you're paying good money for a restored example I think it needs to be bacically original. Otherwise a genuine buyer will spend more than double the cost price to re-restore it.
If I found an HQ example, I would definately keep it original. Dream car right there..!