If you're looking to keep the original PSU case, these are dirty cheap now:
https://www.ebay.com/itm/AC110V-220V...XTn45AHeYfj4zQ
Lots of people use these in various configurations to replace old commodore PSU internals. They're modern switched supplys so usually have some current clamping or such. I dont think there's any such protection in the original PSU's?
John