Gday kevin.303,
Most of the Australian messing around with .303 wildcats stems from the need for a smaller calibre centerfire rifles, and the fact that some States banned the military calibre for sporting use at one time.
There are probably more variations of the .22-303 wildcats than all others calibres (not all Australian), only because those who wanted to produce a serious .22 centerfire used one of the shortened versions to make a more efficient case for the powders available at the time. This usually meant using a Mauser type action to achieve the best ballistics. Those who wanted to keep costs down usually chose one of the full-length versions that would work through the magazine of the SMLE No1 MK3.
Other popular calibres were .303-243, .303-25, .303-270, with the .303-25 being the most popular to the point of having locally made factory ammunition readily available. The performance of these rounds was nearly always geared to the SMLE action and consequently the .303-25 was inferior to that of the .250 Savage.
Larger calibre wildcats were produced but were uncommon, mainly because we do not have much in the way of game that cannot be taken with the .303.
The Epps wildcats offer the greatest variation in calibre, including my favourite, the 6.5mm.
Paul