Historically, boring a 302 was not as finicky a proposition as the 351's were. The problem was casting shift left thinner cylinder walls, but the larger displacement engines created more of an issue with overheating.
But back then at least this was generally accepted to be the big issue at .060" for the most part. Hence the general recommendation to not exceed .040" on a 351W. There were some ways to combat the heat issues, but most were just band-aids if your block was one of the unlucky ones. And completely ineffective if you were REEAALLY unlucky.
But as someone mentioned, sonic checking the block before any boring (a good practice with any older V8 anyway, but very important on Windsors) and will tell the tale on whether an individual block can go to .060" happily, or can't go past .020" with any chance of living a good clean (and cool) life.
Even though the 302's were not near as prone to these issues, it would still be a great practice to sonic-check the walls. Any builder doing volume should probably be doing this automatically so they don't have to eat an engine. They're already selling them for a pretty reasonable price. No sense in losing money you don't have to with a quick check.
I would hope that ATK and Blueprint and any of the other popular builders would be doing this. I'm sure they'd say if they were and anybody asked.
Then again, if a company is using brand new blocks (has to be new to be called a "crate engine" anyway) then maybe the issue is no longer an issue anyway. Perhaps the new stuff is made more consistently, and may even have thicker walls or higher strength materials.
I would run an .040 or .060 302, but if I was going more than .020" with a Windsor I'd be paying to have it checked.
A typical shop charge for sonic-checking the last time I looked was between $60-$100 bucks or so. Pretty cheap insurance when it comes right down to it.
Paul
PS: just re-read the first post and found "sonic checking" right there in the list. I probably would not lose too much sleep over .040" then. Then again, I have not heard of many 302 failures due to over-boring. Those mentioning it here may have had more experience with that though.
