HuntinWidow
If money is tight his 30-06 will work just fine. If you have a few extra bucks to spend let him buy a new rifle.
I hunt in South West Montana. The terrain is open but long shots are not the norm. I hunt with a 300-win mag, I also handload.
I would recommend a 300-win mag or 338-win mag. I also recommend Federal Premium Ammo loaded with Nosler Partition bullets. Every rifle I have shot Federal Premium ammo thru has shot well.
good luck,