Melbourne is 6.5 hours ahead of Tehran
Best overlap: 8:30 AM to 11:30 AM in Tehran is 3:00 PM to 6:00 PM in Melbourne.
Keep meetings inside 8:30 AM to 11:30 AM in Tehran — that maps to 3:00 PM to 6:00 PM in Melbourne. Melbourne is 6.5 hours ahead of Tehran, which gives you a solid 3-hour window. Book earlier in it and neither side is rushing. These times hold for most of the year, but Melbourne's daylight saving (which Tehran doesn't use) shifts them by an hour twice annually.