Hey, If you just ordered from a dealer... did you pay a premium for early ordering. I went to a dealer two days ago and he said he wasn't selling anything for less than 10 thousand dollars over sticker. He says I won't be able to get one for sticker price for a year maybe, "Until the 'New' wears off." Did you have to put up with this crap too?
This GMPP catalog says the LSA is the engine for the Z-28, not the LS9, but both use the 6.2L engine block same as the LS3, except I think the LS9 is cast differently by process. So if you want, instead of selling your whole LS3 you could modify it with new forged internals, cam (which your swapping anyway you say) and maybe check to see if you will need new heads, then add the supercharger. If your not going to boost it up to 600HP like the LS9, then you may get away with using the same block and see if its cheaper than the whole new engine. but if your going to get a whole new engine anyway, the LS9 is more powerful, very similar, and the LSA has a wimpy camshaft with low lift, to provide "Cadillac's signature quietness and refinement." It's all up to you if you have the money, but you may not have to swap the entire engine. Make sure you have a buyer for the old engine first. Don't get the LS7 if your going to Boost it, though, Chevy tried and the walls were too thin to hold the pressure, due to the larger bore, so that's why they went with the 6.2L instead of 7.0L. There's a ton of GMPP engines available, and some may not be street legal.