Yeah, I've seen those on ebay at least ten times.
Don't forget, along with the standard bore block, you will also need a Z-11 crank with the longer stroke. To me that's a pretty spendy "conversation" piece.
Nitrous is for guys who don't really know anytihng about how an engine really runs. They just ead a Summit actelog and ordersomething that says it will add 100hp!