The k24z3 makes more HP stock and has stronger rods, but the lack of VTEC on the exhaust cam means its unfortunately not as tuneable. Some folks in the US have installed the k20 head and oil pump on the z3. I believe PLM make adapters for it. There’s videos on YouTube and info on the various American Acura/TSX forums.
Edit: meant to say I think it is also possible to install the k24a2 head on the k24z3 block, albeit with a lot of modifications. Seems to be quite a ball ache to do as much of it doesn’t line up.