^ aluminum blocks tend to move quite a bit in high hp applications, or so I was told when I looked into it. Further, most of the weight loss gains are seen in big blocks. I had this grand idea of doing it to an LSx 454 and was told I'd be lucky to see a 40 lb weight loss. Not worth it IMO, compared to just using a big bore aftermarket aluminum block like RHS (if you like going around corners)...