UTC/Goodrich list 42305 or 42325 for the 412 and both of these are "Maximum Lift Load 600 lb. (272.16 kg)"
Breeze HS-20200 is the same.
There are 450 lb products out there but you probably wouldn't expect them on this aircraft.
Anyway, as was discussed at IKAR 2012, shock load is the achilles heel of helicopter winching. Tiny events that lead to shock loads can have catastrophic results if the winch is not a modern example with overload clutch protection.