Stock R33 bottom end before I rebuilt it (not due to failure of bottom end, just crank keyway) managed 352RWKW for ages no probs and reved her up to 8500rpm. Serviced it every 5000k and then 3000k's though, oil and filter.
600HP at the crank is a well known limit for a stock bottom end.
Rods are good for 400rwkw plus.
Pistons are pretty good, but will only take so much detonation/poor tuning before they fail.
Crank will take a lot, cars running up to 1000hp.
Oil pump and drive is a big problem with 32 cranks especially.
Blocks are good for a lot, unless bored out excessively, 1991,1992 had issues with cracking. N1 block (24U) is the serious block for big power...
Thats a quick rundown, other guys will add what I have missed. There is also a s%#t load of info when you do a search too.
Cheers.