Hi,
Unless you are desperate to use a Miggy PSU, I would suggest you find an old AT PSU from a PC , AT type supplies are worth nothing in the PC world nowadays..
but run amigas with loads to spare..
They are what's in a Goliath Amiga supply.
You can get them from most old slow PC's, from a dump or whatever, ranging from 90watts up to 250watt, any will do, if you can find one with a mains switch built in even better..
ATX PSU's can be used but are more of a pain to modify.
If its got a standard On/off switch either built in or on a cable then its an AT supply.
Easy to mod as long as you definately have clue about wiring and soldering.. as theres a few high voltages in these.
take care
C.