Stanley and Record both did HSS for Australia and New Zealand. I'll try to find the source but I'm sure I read that they were never all that popular. Of course, these irons do not account for the beautiful work from native species housed in Australian museums and private collections made well before HSS would have been available. They muddled through somehow.
Kunz still make HSS replacement irons that will fit and has provided these for years. Anybody in need of something more robust certainly has had this option for a few decades, at least, not accounting for the Stanley/Record HSS that might have been available in the vintage market.
Here's Kunz that will fit a No. 4 or No. 5:
http://www.pecktool.com/shop/50mm-2-hss ... lane-iron/
And scroll down at the link for HSS block plane irons.
Maybe we need to see a review of these irons, plus the ones Corneel linked to, vs. PM-VII and high end A2.
Alas, I won't hold my breath.
If one is totally freaked about tearout whilst four-squaring some gnarly tropical species, Kunz make toothed blades you can drop in your bench plane then finish up with their HSS for your No. 4:
From England's own Workshop Heaven:
http://www.workshopheaven.com/tools/Kun ... lanes.html
Two Cherries USA has HSS that is a bit less expensive than the Kunz offering:
https://twocherriesusa.com/product/hss-cut-plane-iron/
Mujingfang make their planes with the option of HSS as well:
http://www.workshopheaven.com/tools/Muj ... lanes.html
Kunz still make HSS replacement irons that will fit and has provided these for years. Anybody in need of something more robust certainly has had this option for a few decades, at least, not accounting for the Stanley/Record HSS that might have been available in the vintage market.
Here's Kunz that will fit a No. 4 or No. 5:
http://www.pecktool.com/shop/50mm-2-hss ... lane-iron/
And scroll down at the link for HSS block plane irons.
Maybe we need to see a review of these irons, plus the ones Corneel linked to, vs. PM-VII and high end A2.
Alas, I won't hold my breath.
If one is totally freaked about tearout whilst four-squaring some gnarly tropical species, Kunz make toothed blades you can drop in your bench plane then finish up with their HSS for your No. 4:
From England's own Workshop Heaven:
http://www.workshopheaven.com/tools/Kun ... lanes.html
Two Cherries USA has HSS that is a bit less expensive than the Kunz offering:
https://twocherriesusa.com/product/hss-cut-plane-iron/
Mujingfang make their planes with the option of HSS as well:
http://www.workshopheaven.com/tools/Muj ... lanes.html