I don't have a 325 WSM but I'll try to help out.
Here is some load data from hodgdon.
The 325 WSM is a .323 cal cartridge.
I would go with the heavier wt. bullets many of the lighter ones are designed to open up easily at low velocity (designed for 8mm Mauser).
Sierra has 200gr. Matchking and 220gr. Gameking bullets in 8mm.