LSA-1 is defined in 10.3.5.1
What radionuclide are we talking about? Based on what it is, we can check the max. TBq per 10.4.A (other form).
10.5.B shows that we'll need either a an Industrial Package Type 1 or 2 depending on the state of our radionuclide. This using "Not under exlusive use" (exclusive use is generally military/govt special licences/permits etc etc).
Basically, you need the exact commodity so that you can find it's max. permitted activity. This is then the answer you're looking for. Weight is not a factor (at least for us in the industry - I believe their is a max ratio TBq/Kg depending on the radionuclide, but that is the shipper's job)
Hope of some help.