Your platform is as good as any if you plan on using a long action cartridge. One thing you might want to learn is if your action is stagger feed or center feed. The former has the mag attached to the action and the later the mag attached to the stock. I had read in a previous post you were interested in a detachable magazine and this will help there. The Timney trigger is good as is the Sav I. The Save II is a busy set-up and I have learned to appreciate the SSS trigger.

As far as making an ethical kill at 1000, that requires a lot of support outside of the rifle if t all. 500 maybe is much more feasable. The cartridge is subjective to your intended prey. A magnum case is ideal but it can be done with something like, say a 280 Remington