for More Power:
Lathe off 1mm-1.5mm from the stock head (till the cranking pressure is 135psi) for more compression and power.
Use tubing to extend the intake tract length which gives more engine power at low RPM.
For even More Power:
Make a Jaguar Torque Pipe.
Use JBWeld to redirect transfer port flow more rearward in the cylinder.
For More Speed:
Use a rotary tool to change the cylinder ports for more power and higher RPM (more speed). If vibration is more annoying at higher RPM then buy a lighter titanium wrist pin and drill lightening holes in the piston (or even more troublesome but better: remove the flywheel and drill holes in it for better balance).
Buy a Rock Solid reed valve and ask them to size the part where the carb connects to the reed valve for the needed diameter for your new carb (or just have your machine shop make one if necessary.).
(read all my other pages for details on above suggestions)