I'd be willing to bet that the parts manual for the oil filters doesn't refer to "LS1" alongside the relevant Holden models where that engine is fitted. It's more likely to simply have two listings - one for "V6" and one for "V8". Certainly, the parts catalogues I've looked at are printed like that. I don't see the VZ being listed as "Alloytec" or "LS1". For the VZ, where the engine changed mid-model from the 5.7 to the 6.0 litre, it would probably list 5.7 or 6.0, or models up to a certain date, then models after that date, if the filters were different.
So Savage1987, instead of trying to overpower the shop assistant with knowledge, why not just ask for a filter for a "VX/Y/Z V8"? Would have saved some hassles, I imagine. And knowing what filter your own car uses would have overcome the problem of going home, draining the oil, THEN finding out that you had the wrong filter. Just imagine if you had taken the time to know what the filter number was before you went to the shop - you could have just given him the correct part number in the first place and your visit to the shop would have been much less stressful.