Carb tuning

I kinda agree. Once you star changing PARTS, you really certainly ARE tuning. And I'll also say this. With stock and milder builds, the chance of one being right out of the box is greater. When you start having big intake manifolds, free flowing headers and exhaust, more compression and more cam, that's when you actually need to start tuning. Since I tune old school by reading plugs and feeling driveability, I can have a month or two into getting one tuned correctly. ......which is how I actually prefer it. I've thought about an air fuel gauge, but as long as I can tune "my way" and get it right, I'll continue to.
I agree with this. Plugs are more accurate than a A/F gauge in an exhaust pipe because you are reading each cylinder separately instead of a bank of four. Also, like you say, smell, ears, and feel are great assets to tuning. I also agree that the closer to stock an engine is, the closer a typical "600" will work OOTB.