ok here's the deal from what i can tell:
the z24 usues the same motor mounts as the KA but dont qhoute me on that one just yet. and the only really big thing you have to do to drop an sr20 in there is dent the firewall some to make it fit. ive been trying to figure the same shit out as you as i have an 99 with the z24.
but a piece of advice, if you arent gonna do the swap fairly quickly, the z24 is a pos motor that is nothing but headaches!! i mean 8 plugs and 4 cylinders?!?!?!!?