The Caddy weighs less than the Stovebolt, or GMC six in my case, that it replaces. Its about 650 pounds depending on exactly how its set up.
They are a high nickel content block and reports are that they go a long way before showing any real wear. Your question implies a timing question and I don't really know much about any Caddy motors except the 472/500 so I won't try to respond outside that context.
