Im wondering if the article in the 12 Port News might have been meaning the engine used 307 pistons instead of 327 pistons. Its well known by most in the Inliner community that a .060 overbore is the maximum safe acceptable limit for most street and race engines. And even in some race applications that are pushed out to 4" don't live long or yield the results they were expected to. Core shift will always be a factor and is present in all blocks. In my opinion, you are just throwing money away to go to a 4" bore. Like Stroker said, sleeving removes too much of the parent metal to securely support a sleeve at that bore size.
