My "B" Block needs a bit of work.

[Purdy Swoft]

As Jim Brierly says , there is nothing wrong with a 4 inch bore . If it was mine and I could use the block without sleeving I would, even if it was just a little lose . If the valve seat crack could be done without having to sleeve the cylinder I would do that . Even if you had to sleeve one cylinder , it wouldn't be as bad as sleeving 4 . It may hold up better and run faster this way.