If you are looking at building a custom rifle, then I'd look at the 6.5X47 Lapua.
I just finished one for my kid and I'm having a hard time not keeping it for myself. I'm shooting 120gr ballisic tips in a 21 inch tube.
1. Light Recoil.
2. No brass prep.
3. Efficient in a short barrel.
4. Very accurate.
5. Good barrel life.
I would also consider , where you hunt . Woods vs long fields, maybe even
hill to hill. Benchrest loading techniques can be applied to nearly any
cartridge, at practically the same outlay in dollars.State game laws may
overule many good cartridges, such as was recently posted about
Indiana and 35 caliber being a minimum. I fail to see any logic to that.