From everything that I've read, the cam and head combination is the key to achieving this.
Cam Lift seems to be the term everyone is interested in, but it really just determines how far the cam lobe will open the valve at its peak (think increased flow).
Cam Duration is the other term I hear alot of. It just measures how long the valve will stay open.
A top notch builder will be able to custom grind an off the shelf cam to match up the valve events in order to maximize the power where you want it.
Advancing the cam (by grinding the cam core or installing the cam with offset bushings) will increase low speed torque at the expense of peak HP. This moves the valve events earlier in the cycle. Combined with the Intake and Exhaust durations, you can modify the valve events to minimize overlap and maximize volumetric efficiency. To get a tree stump puller, you want to open the Intake late and close it early and open the Exhaust late and close it early (I think, but correct me if I'm wrong).