Went through the same exercise about two weeks ago.
If you want a rattle can, finding the correct colour in Australia is very difficult. While several paint suppliers (e.g. BCS Auto Paints) can supply a rattle can, they require a paint code. They will not colour match for a rattle can because the amount of paint required for a rattle can is so small that colour matching is not worthwhile – too much paint gets wasted I believe. This was explained to me about two weeks ago when I was trying to get a rattle can coloured matched to my ash try for exactly what you want – repairing the dash.
Depending on how badly the paint is scratched on your dash, you could try model paints from a hobby shop.
Alternatively, try to find a code for Parchment that makes sense in today’s paint world. This might be a code from a modern car that is very close to 1966 Parchment. It could also be a non-vehicle paint code or formula – go to Bunnings, look at the house paint colours on the cardboard swatches.
Try an off-the-shelf rattle can from Bunnings or a hardware shop – Gloss Ivory or Heirloom White might be close enough to parchment.