7MTT and SnapMirror are the way to go if you can. 8.0.x created 32bit aggregates by default, but they can be in-place upgraded to 64bit if you upgrade to 8.1.4P4+. Then you can use 7MTT to orchestrate the transition to 8.3.x. 7MTT will assess the environment for potential issues, automate most of the configuration, use snapmirror to copy the data, etc.
If you can't upgrade, or you just want to do it by hand, you can. Just recreate the volume and qtree layout using the same language settings as the source and recreate the shares. From there its like any other file based migration.
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