Drift tuning

Is there a special tune you’d use for an ls3 drift engine?

Nope, the engine doesn't really care what it's doing provided the fuel and ignition delivery is correctly optimised. About the only thing I'd be mindful of is that a drift engine is likely to spend a lot of time on the limiter so you need to consider how this is set up. Particularly for an engine with a hydraulic lifter like the LS3, I'd recommend a nice gentle limiter using a fuel cut instead of ignition cut.