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(sigh)
will the bore vs stroke "debate" ever end?
torque is largely a function of displacement(regardless of bore/stroke) and compression(not just static compression, dynamic is the key here).
horsepower is calculated from torque at RPM, nothing more.
with VERY few exceptions(all of which are still labratory engines, IIRC) bore/stroke doesn't change(though # of effective cylinders can in certain engines), but you can certainly alter dynamic compression(and some engines even change static compression, but i don't think any are very common).
nearly everything these days uses VVT, which is a good example of that. throttling also plays in as well.
anyways, point is, if you want more torque, you need more dynamic compression or displacement. if you're looking for more power, you need to be able to stuff large amounts of air(and fuel) into the cylinders at higher RPMs, since the horsepower equation "favors" higher engine speeds(since producing the same amount of torque at 2000 RPM compared to 4000 RPM is a doubling in horsepower).
so, in the end, compression and displacement determine torque, the ability to keep large amounts of air flowing at higher RPMs determines HP. the fact that engines that have more bore than stroke GENERALLY do better at higher RPM is due to it being easier to keep airflow up with larger ports that sacrifice low RPM volumetric efficiency(which plays a big part in dynamic compression). there are methods to keep airflow coming at higher RPM without sacrificing low-RPM operation, but they're less "simple". they are becoming more mainstream though(VVT, turbochargers, multiple intake paths, etc).
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