Tyres for older bikes ('80s)

Apologies if this has been asked before, checked and couldn't find an answer.
I'm looking for 2 new tyres for an FT500:
-3.50S19-4PR, I believe is now called a 100/90-19
-4.25S18-4PR, now called a 120/90-18
... what brands still make these sizes and is there a recommended place to buy - preferably in Melbourne.
Appreciate your help.
Thanks,
Tony
I'm looking for 2 new tyres for an FT500:
-3.50S19-4PR, I believe is now called a 100/90-19
-4.25S18-4PR, now called a 120/90-18
... what brands still make these sizes and is there a recommended place to buy - preferably in Melbourne.
Appreciate your help.

Thanks,
Tony