I know this is an old thread, but I just pulled my first ls1/T56 combo from a VY SV8 so thought I'd comment as well.
I pulled it out from the top complete and it seemed pretty straight forward. Took half a day, most of the time was spent chasing wiring harness plugs and disconnecting those bastard fuel line connectors, but used a bushman mechanic tip I found on youtube and used a coke bottle lid to pop them off without breaking them.
I left all the accessories on, just removed the radiator and hoses, intake and fuel rails, air box and right side coil pack to give clearance for the motor and the brake booster.
Took the extractors off, undid the clutch line and the most annoying part I think was having to unbolt the tailshaft, I'm used to that just slipping out.
Other than that I just drained the sump and power steering and the clutch fluid decided to let itself out all over the garage floor, but it was pretty much it.
One tip though, my engine mounts didn't want to let go so once we'd hoisted the weight off the engine bay, we ended up undoing the bolts to the motor and that made it a lot easier to get the engine clear, and an engine level on the hoist made the job a lot easier getting it out too.
Overall it felt easier working on this than pulling the 400 from the transAM so hopefully it'll be easy putting it in that.