Gundog
I have been experimenting with AR2208 powder and 400gr frontier bullets in my Ruger 416 Alaskan.
On another site it was suggested to use the 416Rem starting load as a starting point for the 416Ruger which is 72grs Ar2208. I started with 74 grs AR2208 and currently am running with 77.5 grs AR2208 for 2378 fps but that is with the design bullet I am using. I am using a magnum primer to get them started.

You should be right starting at 74 grs and working up looking for signs of pressure as you go.

The new Hornady volume 8 has load data for the 416 Ruger but dont think it has ADI powders and it may not be avial in Oz as yet.

Some reloaders have purchased the number 8 edition on line from overseas.