you blokes give up too easy. A 98 barrel and 96 barrel have the same shank length and thread pitch.Turn down the 98 barrel 1/8" in diameter and you will clean up the original thread to about root diameter, index your thread cutting bit to align with the remains of the 98 thread and cut the 96 thread.Fit to 96 and adjust headspace. The 96 magazine is long enough to take 160gn projectiles in 6.5 ,so it will take 8x57 ok.
A 308 pushes 180gn projectiles at 2620fps for a ME of 2743 .
8x57 does 196gn at 2780fps for ME of 2780.
IF a 96 can handle a 308 it can handle 8x57-the ballistics are virtually the same and as the 308 does it in a smaller case then in broard brush terms it is running at higher pressure.
Western fire arms has reloading dies for the 8mm at the same price as 30/30 or 308 . ex mil 8mm is available for about $30/100 ,PMC and Highland have cheap 8mm brass.8mm projectiles are about the same price as the other cal's.
The 8mm wins out in the top end if you look at Taylors KO figures the 140 gn 6.5 has a value of 15, the 150gn 30/30 is 16, 180gn 308 is 21 and the 196gn 8mm is 23.
Your idea of a short cheap fast handling scrub gun is a good one(should have some knock down power as well). I have been converted to the Red Dot scopes after using a mates 45/70 with a Tasco Pro Point red dot .Fit a weaver style rail on the action using the holes you already have tapped. The Tasco pro point sight has 30mm tube and using weaver style mounts you can fit it just far enough forward to clear bolt handle and the bonus is that the great Mauser safety will still work.
Dont do the scope forward of the action in scout style, this is a wank as it destroys the balance and fast handling concept of a scrub gun.
If I were a Sambar ,Hog, or Camel I reckon a 220gn 8mm Woodleigh planted up your ring is fairly gunna make your eyes water.
30/30-under powered
308-boring
6.5- even more boring
JMT
If you dont use that action send it over here, I have a use for it
Cheers