Block stitching needs to be done with cast iron tapered plugs, not steel pipe plugs. There's enough heat expansion difference to create more cracks (and leaks) if steel plugs are used to stitch a block. Goodson, K-Line, and a couple of other machine shop supply places sell the tooling and the plugs, but they're expensive. Unless you're in the auto machine shop business, another engine or maybe a patch with Marine-Tex will be a better idea. Fortunately, you don't have to seal against 15 pounds or more of cooling system pressure.
Jerry
