I would not be afraid of a serious build in the right 400 block.
The problem now is finding a "good" block to start with. Unless you have it sonic checked you have no idea.
I had 4, and 3 ended up in the junk pile because they were cracked, or too thin to even bore .030 over.
I've experienced the same thing on the 400 blocks, sonic test all cylinders before going forward before starting any build
The first 400 block I built for a customer said he had the block sonic tested and was told it was good, it split the #1 cylinder on the cam side. on the 3rd or 4th pull on a DTS engine dyno, we tried sleeving it on that bank after sonic testing it and found it was unusable based on the massive core shift, that bank cylinder wall thickness was right at .035 thick. The sleeves wouldn't seal on the bottom
