You need to use the manual bellhousing that was attached to the L series and have it machined to work with the KA gearbox.The KA bell housing is just slightly off.
When my fiend was heling me do my clutch and flywheel, he had a spare KA tranny laying around and it was just off enough to not be able to work (although we were tired and didn't try super hard to line anything up while the engine was in the car, I'm sure we would have tried a little more if it was out of the car.)
As for the 5 speed swap, you need everything from the clutch pedal assembly, to the tranny/driveshaft, and everything in between( clutch mc, hardlines, slave cylinder, flywheel/clutch, tranny mount etc.) I'm currently gathering parts for my 240sx 5 speed swap. I mean I have an auto 240sx, and I'm converting it to 5 speed, not a KA 5 speed swap in my datsun.