The problem with the Caddy motors is that, in my experience, once the heads have been off, the (removable) cylinders don't seal well at the bottom of the block and therefore it's not really practical to attempt to replace head gaskets because it could easily end up as a complete rebuild (difficult on a Caddy motor) or a replacement engine, all under warrantee. Losing deal for the shop, usually. I'd recommend a replacement engine, I hear that the Jasper rebuilds are OK but but I've never had the opportunity to use them.