I like the LS1 because it weighs about the same as a Toyota V6, it's got electronic controls (I like electronic controls over carbs and vacuum advance distribitors), it's efficient, and it won't need headers. You'll want an overdrive automatic for the highway if your going to daily drive, so forget the Turbo 350/400. The 700R4 and 4L60 have non-electronic versions that should bolt right up to the LS1, but I'm not experienced with these to tell which to choose.

For axles try Diamond axle in Colorado. They might be able to make you a 9.5" axles out of Tundra and Landcruiser parts.