Both are equally accurate.
Come on Jerry, you'd need a flame suit on if you said that on Benchrest Central.
JEC, what do you want to do with this gun? Single shot only? How far do you want to shoot? How accurate do you want? Do you want to learn all the necessary things to really get the accuracy out of a 300Y and less 6PPC ?
If we're talking about short range shoots with those that know what they are doing the 6PPC wins GROUP matches 99% of the time.
Long range 300+ is a totally different story, you want heavier bullets (~105gr) going quick, which means faster twist barrel. It's worth the accuracy robbing gun torque with the 1-8 twist since you win in the less wind drift area.
The 6PPC is best with 68gr bullets and a 1-14 twist.
As you know the PPC case (220 russian, 7.62x39) has a slightly smaller head than the 30/06, 308, 243, etc etc family. I and many many others have made 6ppc's with just an unmodified bolt from a .308 family Remington action.
I heard ONCE that a guy had problems with it clicking over the rim and not wanting to extract, I've never had a problem and I've loaded hot at times looking for better accuracy with no problems. Useing the 308 rem bolt is not a safety issue.
I'm just got the barrel for another ppc project I'm doing with yet another Rem action.
Give us more info on what you want to achieve and we'll give you better answers.
For myself I'd like to hold in my hand a .308 Savage bolt and a ppc case. Likely a better gyppo target action over the rem.
Mike