It's 1933 and the governments of Australia and New Zealand are getting twitchy about the ambitions of the Empire of Japan. You are tasked with making recommendations for how their militaries can prepare for a potential war. It is of course assumed that the Mother Country will be fighting alongside them but it is requested that they are able to rely on their own resources as much as possible and steps be taken to maximise the input of local industrial capacity.
There is mileage in sourcing heavier equipment from the motherland where the far greater industrial might allows for superior products in terms of quality and quantity as well as the time it takes to build it makes sense.
However as the OP points out this becomes problematic in times of war when the Motherland ability to supply equipment to Australia might suffer from competing resource issues.
To that end it does make sense for Australia to have the ability to build certain items in line with the rest of the Imperial armaments.
So I would certainly do the following - taking into account its the mid 30s with the equipment coming into service in the late 30s
Bren gun production (as per OTL)
Prepare to switch to No4 Lee Enfield Production and later No5 Production as soon as possible - the later Lee Enfield's were designed to be easier to make using modern techniques - OTL Australia did not switch production and continued to produce the SMLE - the No5 despite its undeserved reputation for having a wondering zero should replace the No4 ASAP. In the interim before the No4 is adopted upgrade existing rifles and any new production to No1 Mk V with the rear aperture sight during the late 30s
Vickers MMG production (as per OTL) - the Australian army retained Vickers at both Battalion and also like the rest of the Commonwealth forces had independent MG companies within the Division - thus a given Australian Division had more Vickers MMGs than its commonwealth peers.
2" Mortar (Not sure if Australia produced their own - do so if not)
3" Mortar (Not sure if Australia produced their own - do so if not)
3.7" Howitzer - this gun makes a lot of sense for the Aussies until the beginning of the war and beyond Australian forces are not going to be mechanised and would rely on Horse and mule for transportation. The 3.7 breaks down quickly into 8 parts and can be put together in 3 minutes.
Bofors 40/60 (As per OTL)
AFVs and heavier equipment
Build Universal carrier as OTL
Buy the licence for the Vickers 6 Ton Type B (2 man gun turret) and develop a version to use the Australian made 3.7" Howitzer, using the home made Cadillac V8. To be built at the New South Wales Railroad company - 120 tanks are built between 1935 and 1940 before production switches to the Valentine
25 pounder gun - as per OTL but start earlier if possible - to be built by Charles Ruwolt Pty Ltd, of Richmond, Victoria, and General-Motors Holden's Ltd, of Pagewood, New South Wales.
Stand up production of the Valentine in line with the Canadians i.e. during 1941 - having already been building the Vickers 6 Ton tank (Which was actually closer to 8 tons) - the builders at NSWRC have a good relationship with Vickers and are able to leverage that relationship to rapidly switch production and again build 'CS' variants with the 3.7" Howitzer as well as the 2" AT gun armed tanks.