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 Performance 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 have your machine shop make a custom intake section (where the carb clamps on) if necessary.
(read all my other pages for details on above suggestions)