Lars, I think it is impossible to say and depends on what you want/expect and most importantly can do testing and engineering wise.
Twin carb race engines on Spa do go bang with 2cv cranks, however yours probably doesn't get so abused.
Moreover natural asperating engines may get hotter than turbo engines with the same power. At least (more) boost pressure = more volumeflow, gives cooling to some parts (for example exhaust), but raises peak cilinder pressure. So the turbo may reduce thermal load, but increases mechanical load on the crank.
Where this tradeoff gets too bad is impossible to say precisely. To get a good answer you need to test your setup by trial and error or on an engine stand. Although that is obviously not what you are after...

p.s. revs are a fine way to get more power as long as the engine construction can handel the higher speeds of all moving parts. The picture of Ken shows what happens when it can't