Hi Rowlie,
I agree with Nell - it should go to the relevant county archive or record office. Perhaps donors (such as yourself) can request that the donation be digitised as a priority, or at least written into the workplan, so that you know it's going to be of some use - particularly the personal information contained therein.
Maybe you could also photograph or scan, or even just transcribe, the Throsby info and post it here in a new thread. Someone might pick up on it and find a connection.
Cheers
Prue