Just a point about "modern" 8mm ammo. The light-loading applies to all Rem/Win/Fed ammo along with any commercial Prvi Partizan(PPU) ammo marked as "8mm Mauser". PPU ammo marked "8x57 IS", all S&B, Norma, Lapua, and Hornady are all loaded to where 8x57 JS should be, a.k.a. CIP spec instead of SAAMI.
If you see ammo marked "8x57 I", "8x57 J", "8x57 JRS", or "8x57 IRS", don't get it. Without the "S", it's the smaller 0.318" rounds. With the "R", it's the rimmed version usually used in break action guns such as double rifles and drillings. The Europeans figured out how to do the designation so that they didn't have to download the rounds to prevent them from blowing up older rifles with the 0.318" barrels. And, no, I've never seen one that wasn't modified including every M88 Commission rifle I've ever seen.
I've the most common chambering that I have is 8x57 so I've been through my share of surplus before I started reloading. The most accurate surplus I've found is Yugo M75 sniper rounds. It chronographs about 150 fps slower than most earlier Yugo surplus also using a 196 gr FMJBT, but more accurate. It's still available in quite a few places and I think it only ceased production in the last 10 years. (I might be wrong though.) I haven't shot the Romanian surplus at all, but there was a batch of new-production Romanian that was so out of spec that it wouldn't chamber in most guns. I think that was about a year ago.
Another note on Yugo surplus: It usually has harder/deeply seated primers. I only had one gun that wouldn't reliably fire it and, as someone already mentioned, a new firing pin spring solved that problem. (applies mostly to the 1950's era surplus which isn't really available any more)
I started handloading when the surplus started to dry up. I got a bunch of blem 200 gr nosler HPBT bullets that I use to duplicate the surplus loads, but with much more gooder accuracy.
My hunting load is a 200 gr Partition going at just a hair under 2600 fps.
As for the K98 specifically, if you get some of the neutered Win/Rem/Fed rounds, you should hit fairly close to point of aim at 100 yards with the battle sights down. Off the top of my head, the velocity on those is about 2200 fps with round-nose bullets. I've only got one actual K98k which is a Yugo capture. It has a very smooth action, but not as nice as my Argentine 1909, but still really smooth. It shoots really well also. My eyes are getting a little too old for the iron sights on it, but it's still a lot of fun.
If the stock is too short for you (common problem), a slip-on recoil pad is a great add-on. I've got a couple and they bounce between the mausers and mosins to preserve my shoulder.
Matt