Well to conclude this thread, the old girl made it to the snow and back admirably:
The roof box was for the luggage (and skis while we were there), and the boot was full of 150L of WVO, which was nearly enough for the entire trip! Even with this heavy load and me + 3 passengers it ran great on the Hume Highway, cruising at 110-120km/h. Going up the steep road to the top of the mountain (with slightly less load, as I left the WVO and luggage at the hotel in Mansfield) was also a breeze.
While I was there I used pump diesel in the startup tank and WVO mixed with some home heating oil in the main tank. Temps got down to around -2C, but I didn't leave it on the mountain overnight. It started no problems at the end of each day after 8 hours at the top of Mount Buller.
I've only just refilled the startup tank with 100% biodiesel and this morning (which was quite cold for Sydney) it started in a couple of seconds after one glow. Much better than before. So I'm pretty sure the new injectors have made a big difference there. The pencil style glow plugs also must have helped, but not so noticeable before I changed the injectors.
Apart from that I've not noticed a huge difference. Less smoke when running on WVO, but no noticeable improvment in power or engine noise. Not that it was bad anyway. But I'm glad I did it, as I'm pretty sure they were the originals (judging by the state of them and how hard they were to remove/take apart!)
One tip for anyone thinking of doing the same - I followed the guide on the Dieselgiant website, but I couldn't take the injectors apart by clamping the hex portion in the vice and using a 22mm spanner on the upper portion. They were way too tight. So I simply turned them upside down and clamped the 22mm part in the vice, using the 27mm deep socket with a breaker bar on the hex portion. Easy! You just have to be careful the socket does not touch the nozzle tip and damage it (mine just cleared it).
David I'm pleased to hear your "Italian Tuneup" helped with Helga! The nozzles I bought were Bosch ones (made in India), which I think are the only ones you can get in Oz these days.
1979 300D W123 Running WVO in 2 tank Fitian conversion (since Apr 08 - now dead - RIP)
1990 300D W124 Running a diesel/WVO blend (since August 09)
1988 300D W124 Running a diesel/WVO blend (since Sept 13)