Have you sonic checked 360 or even 318/340?

More often then not, blocks bored to .060 over are going to have some thin areas due to core shift and water jacket corrosion. One needs to make a judgement call as to whether the block is usable based on the intended use. I'm currently running a 72 model 360 block that at .040 over is thicker than most all the other 360 blocks I've ever checked. I almost passed it up once I found it was .030, but luckily I hauled it off anyway. There are a lot of second hand myths and wives tales out there on this subject.

To more specifically answer your question. Yes I have seen 360 blocks that would have certainly failed at .060 over. They never got the chance to though, because they were weeded out by sonic checking.