Selecting a power supply for a device with 625A 1ms peak current
If they do not support active current sharing but suppport passive current sharing with adjustment then it may be possible.

Passsive current sharing requires that there is some diode internal to output so it is back-drive protected for power-up, transient and power glitch situations.

You need to specify your load for these conditions. Latched shutoff?  e.g. requiring operator intervention, or autonomous. 

It depends on your step,load specs for voltage error tolerance.

You may also have power on surge current limits as these are 30Aac each and you may enquire if this can be reduced with ZCS triac on input with bypass timer relay.

Lambda do make good supplies but cooling must be examined and a full design spec verification of your system under all foreseen circumstances for environment and power quality exceptions.

The best design is only based on your best stated requirements and DVT plan.  I have done this before with Lambda and others, so feel free to inquire how.