the stock ka24de is 9.3-9.5:1 cr or so correct? many people use stock pistons i think you should go with those. I dont know the exact cc of dish on z24i pistons but those could possibly lower your compression a bit. Premium pistons dont cost to much more, my distributor doesnt carry them yet but it looks like they are on the to do list
http://www.itmengine.com/pistons.html . You dont need premium rods, seriously, yours if in un-damaged condition should be able to withstand lots of hp.
btw. yes the main and rod journals of the crank would be ground, not the block or rods. So it would become "undersized" and need the appropriate sized bearings.