a .100" oversize for a street engine is a big mistake, in my opinion. I've seen race built 235's bored .125 over, but those engines aren't expected to last long. 261's have "siamesed" cylinder pairs, meaning that two cylinders share the same casting- - - -no gap between cylinders 1 and 2, 3 and 4, and 5 and 6. Block warp isn't going to be much of an issue if any of those pairs happen to get sleeved because one cylinder braces the other one. The stovebolt block is extremely rigid anyway, not at all like the thinwall cast blocks made in the past 30-40 years. Which cylinders are pitted badly enough to require sleeving?
Another thing to consider- - - -if your machinist is only going to increase the bore size by another .020", that means the pits he's trying to remove can't be deeper than .010"- - - -that's all another 20 overbore is going to cut on the radius. I think that's a very bad gamble.
Here's a suggestion- - - - -ask your machinist how many sleeves he's installed in the past year or so- - - - -the answer might give you an idea whether or not he's familiar with the process, and possibly an insight into why he's reluctant to try it. Doing it right is a disappearing skill set.
Jerry
