I called TransGo about a shift kit for the 5EAT. They said they would do it for $350 and would like the valve body for a week or two. Sounds like they want to make a custom kit, but need a valve body to create it. They said that the Suby 5EAT valvebody should be close to the kit needed for the 350Z - part #RE5RO5A-HD2.
http://www.transgo.com/rpg_nissan.php
I could hear the TransGo folks talking it over in the background. They came back and said that the 350Z kit was complicated and they had several people have trouble installing the kit. They did not recommend anyone but an experience professional installing that particular shift kit.
Looking at diagrams of the kit on the web, it did not look overly complicated however.