I basically agree (although I really do like HJ Sandman), but this is my suggested perfect combo:

HQ Kingswood Sandman for ute or Belmont Sandman van (in colour of choice).
If not a ute, use the Kingswood spec hard trim that HX and HZ van got (chrome tail-lights, scuff plates etc).
HZ dash, controls and trim but with HX silver fascia.
HJ-HZ retractable seat belts.
RTS suspension off the HZ or WB range.
HJ's higher performance 308 (HJ 308 was the highest performance Sandman applicable engine).
Gearbox of choice.
Air.
Steer.
LSD.