Way to many variables man.
Depending on compression ratio, fuel, boost, airflow quantity, ignition timing, AFR's. At the end of the day as long as the tune is safe, and the rods, bearings, pistons etc have been upgraded it could be anywhere from 400rwkw+
However there is always a weak point of an engine build and thats usually the first thing that will let go.
However if the head is standard, as in nothing upgraded, cams/springs, id say that is what is going to stop you from making more power.