Jaguar M, if it can be operated from something as small as a Majestic, failing that the A4S from Singapore with the engine from a Hornet sans afterburner.
Jaguar M was a bit underpowered, which was the underlying reason the French didn't buy it IIRC. If underpowered, it's not going to operate from a Majestic I'd think.
Using A-4's was my choice. The cheapness and possibilities of upgrades (quite a lot actually, onsidering the size of the A-4) make it a nobrainer with hindsight.
Still, however many bells and whistles you stuff into an A-4, it's obsolete compared to a 4th generation fighter.
That means you eventually end up in the situation the Brazilians are; they've got a carrier capability, but their carrier is of limited use.
If it's small carriers the Australians want, they could choose to go STOVL later on in the '80s and replace their old carrier with a CVS and go Harrier, although that'll cost a lot.