piston questions

Ok let's try this again now that I have some wifi...
Jeff definitely gets why I never really cared for a 360.
But I've always wanted to try to build one the way Mopar should have.
And Jeff while you're out there .. you and me run alot of the same section of roads... Who do you know around here that even does balancing?
My last several jobs that I have needed machine shop work have gone to newco performance in kentland. Nice and easy 15 min from work.... I'm not sure they do balance work, I know the last time I had to have a crank ground, they farmed it out somewhere. That's been a few years.
That's the old Larry Young machine shop.
For my usage I don't think the cast crank will hurt me too bad, though I wish they were neutral balance.
Now to figure out which pistons to run whether they're stock replacement, or the ones my kid has or something else. We're the magnums as far off of specs like "advertised CR" as the older engines were?
The last engine I did was a/6. And after much machine work it's right at advertised CR, 8.4:1 as measured out, CC'd, by me. Without 0.100" off between the head and block my particular engine would have been below 8:1 as built by Mopar. Quite a ways off. And how accurate are piston makers' CR estimates with "their" pistons and a given combustion chamber CC size?