We have done extensive testing on a variety of 4 stroke motors. The HS 142 is slightly faster on top end than the Honda, however the Honda has more low and mid rage torque. Torque is the force that moves the bike, not HP. Of course you do need HP to make it all work.
Sadly, the choice of workable drive systems is limited. There are 3 American Companies that make GOOD drive systems, Stanton, GeBe [not Grubee], and EZM. The EZM Q-Matic was designed for use on the Honda GXH50 and the HS 142 motors, and has now become a popular choice for the larger 4 stroke motors from Harbor Freight. Q-Matic and Q-Matic Pacesetter drives use an automotive wedge belt [normally good for 50,000 miles] in the primary and only spin the Max-Torque clutch at approx 1/3 motor speed for maximum power transfer. We designed the drive so replacement parts could be purchased from many different sources if needed [Ace Hardware, NAPA, Grainger, etc, etc.].
In conclusion...........Both the Honda and HS motors will supply enough power if used with the correct drive system. We just tested a stock motor [new, not broke-in] and managed to hit 41.5 MPH on the DYNO with stock drive ratios.
Have fun,