I have successfully performed two L28ET into S30 swaps. Both were into 280Z but my experience in both cases revealed faulty ECCS connectors. Horrible running, popping, poor idle, rev-limiting, lean running, all of the above are symptoms of bad connection at the two ECCS plugs.
When you get to that point, push and pull each wire, directly at the back of the connectors, with the car running, and you will instantly identify the problem areas. Adding dielectric grease, and carefuly "preloading" the pins in the ECCS connector by slightly bending them to one side, seems to alleviate the issues.
Not sure if it helps, but I have a pretty simple wiring schematic for the swaps over in the downloads section of hybridz.
http://forums.hybridz.org/files/download/4-turbo-swap-wiring-diagram/