LOL. I have flash blindness from the light bulb going off over Stevo's head all afternoon! All I did was act as brick wall to bounce ideas off.
Haha don't be so modest mate I would have been pretty screwed without your help.
My mechanic came over today and together we pretty much fixed everything.
The first thing he did was go over the entire car and ensure that it was fit to drive 1000km to Sydney. Apart from the rear tyres he gave it the thumbs up. Then we dropped the oil in the engine and replaced the oil filter at the same time.
After I had told him how good the engine was running the previous day thanks to Mike, it barely started and when it did it was backfiring out the exhaust and spitting out the carbs consistently. He said straight away: One of your cylinders ain't firing, lets check your plugs and leads.
All of the leads to the plugs were A-OK for resistance, but when he tested the coil->dizzy lead he found it had far too high a resistance. But replacing this did not fix the backfiring or spitting. He looked at the plugs and said, 'NGK HP6ES? You need hotter plugs!'. So off we went to supercheap to find some NGK HP4ES plugs. In the end they didn't have any in stock at supercheap or Repco but Repco had Bosch plugs that were equivalent to them so we got 6 of those. With these new plugs the engine ran much better with all 6 cylinders firing, the backfiring out the exhaust stopped and the spitting out the carbys stopped as well (or so we thought).
I then found that if the accelerator was engaged quickly the carbs would start spitting again. My mechanic cleaned the points and adjusted the 'dwell' to be the correct level. He then adjusted the timing from 8 degrees to 10 degrees advance.
After this the engine ran beautifully with no flat spots even at low RPM. We took it for a test drive and it felt like a new car. It still 'spat' once, but we were on a steep hill and at a low RPM. Otherwise I am very happy with the way it is running and hopefully it won't reset and run like crap tomorrow morning.