This is a great rifle, most are extremely accurate right off the shelf. I have not used that particular scope but have shot a lot of the Nikon 3-9 and all were certainly adequate.

Calibers, I have shot the 22-250 mostly but have started shooting the .223 more lately. Out to about 300 yards you should not see any huge difference in killing power. The biggest advantage I can see with the .223 is the ammo is often a lot cheaper, especially in the bulk 50 packs. Also, if you reload the powder cost is less because you use less.

Have fun picking out and shooting that Savage.