Hello currently looking at setting up 480 volt 1000 watt high pressure sodium ballasts. Primary power is 600 volts 60 amp. From that what is the max amps I can use at 480 volts? A qualified electrition will be doing that part... then the trick will be working with the wiring and setting up timers..

A 480 volt 1000 watt HPS fixture draws 2.3 amps each.

You will need a 3 phase transformer to bring the 600 V 3 Phase down to 480 V 3 Phase. A maximum of 45 KVA transformer with 600 Volt 3 Ph Delta primary to 480 Volt 3 phase Delta, will draw 43 amps at 600 Volt fused at 60 amps, and provide 54 Amps at 480 Volt fused at 70 amps. You can load this 70 amp fuse up to 80 %, which will provide 56 amps per phase of usable power at the branch circuit level.

Balanced evenly across the 3 phases, you can connect a maximum of 33- 1000 W HPS fixtures, in Delta fashion.

You mention timers. One timer can control one contactor that can switch the feeder , either the 600 volt or the 480 volt. This one timer will then control all the fixtures at once.

A qualified electrician must be doing all the work, including the transformer, panels, disconnects, timers, and branch wiring to each fixture, and installing each fixture.