CFM is horsepower; need more CFM? Rev it higher!. (Unless you're on a Harley; that would feel icky.)
Torque is more closely related to displacement than horsepower is. It's like cars in the 80's: torque creates the sensation of speed, power is sneaky in that it means more in terms of acceleration.
So I'm sure the HD engine has lots of torque, but it also has 60% more bike to push around.
And you can't replace the Iconic Sportster! Oh No! It hasn't been sporty in 40 years, and it has become a rolling joke, honestly; World's Worst performance bang-for-your-buck.
Just realized this HD engine is rated at less than a Blast. What the fuck...