That's an interesting question and there are a lot of opinions out there, and I think that the answer varies depending on whether you are sleeving a cast iron block or an aluminum block.
On a cast iron block, there can be an advantage to going with a very thin sleeve. The reason is that in a case like that, boring the block oversize for the sleeve may not break into the water jacket, meaning that the sleeve is supported all the way around from top to bottom. So you can use a smaller OD sleeve, then bore it out to the desired ID, and leave the sleeve rather thin. Years ago Blair P did a Pond block for me and sleeved one hole that was a little big. I'm not sure what the final sleeve thickness was, but I don't think it was as much as .090", probably only .060" or so after boring to size. On the other hand, the 428CJ I have owned since 1978 was sleeved in 1982 with a .125" thick sleeve. To get that sleeve in the block, boring it oversize broke into the water jacket. That engine has been running fine ever since, and currently is in my daily drive 68 Mustang.
For an aluminum block I like to keep the sleeve as thick as possible, to hopefully minimize any bore distortion. However, not everyone agrees. Mike LeFevers, who designed the Shelby aluminum block, has told me the sleeve thickness can be as low as .060", and he referenced sprint cars as a class where that sort of thickness is common. Recently I visited Kurt Neighbor in Ohio, who is running Kaase engines in a couple of his Pro Mod race cars. He had one torn down when I was there, with the sleeves out, and I couldn't believe how thin the sleeves were; right around .030"! A few years back at PRI I talked a little with Jon Kaase, and he made the same argument, that the sleeve can be as thin as you want, provided there is a bunch of material behind it to back it up. I personally have gone as low as .080" thick on a Shelby block, but I prefer to stay over .090", and hopefully as thick as 0.125".
Bottom line for me is that I'm not sure there's a correct answer to your question, but hopefully this gives you some things to think about.
