Good looking rifles.
My buddy has had a 6.8x68 for 45 years. Good ctg, especially if it has a normal 9" ROT. Some of the commercial rifles only had a 12" ROT which was suitable for light, short bullets only. Seems to me a factory load for it had a 93gr. bullet running 3,700fps.
Since ours seems to shoot the 123gr. Hornady, it might have the 9" ROT, but then if that is a 50yard group, perhaps it's the slow twist.
If the faster 9" twist, the 129gr. Hornady SP at about 3,200fps to 3,300fps is a good long range goat or sheep rifle - deer too, I guess.
I chambered one up on a 6.5x55 Model 96 action and barrel. Had to partially pull the bolt to eject a live round. I only ran the 129's at 3,000fps even in deference to the action. Shot under an inch though, at 100 meters.