Actually, the 8mm ammo is underpowered because of the Gew88 Commission rifle... Even the Late War Concentration Camp produced K98's will handle regular hot 8mm loads (as long as it hasn't been sabotaged)
The M48 would make a great rifle for your son to shoot!

It may not have the history of the K98s, but it has the pedigree, and is a safe and reliable action! Plus, gorgeous to boot!
I would suggest buying a commercial made Sporting rifle for hunting though, it will in most circumstances be cheaper than sporterizing the M48, and will most likely be much more handy and accurate than the M48. Plus, you won't lose any monetary value in the M48 if it isn't sporterized!
Get him an M48 for open sights close up shots, plinking, and the history. Then buy him a Zastava Commercial M98 for a hunting rifle! Same action as the M48, but already in the Hunting configuration you will want! (Drilled and tapped for scope, Nice Sporter Stock, side safety, hinged floorplate) http://www.shop.tradeexcanada.com/content/zastava-commercial-m98-30-06-1
Cheers!