ACL makes a nice piston. Never had any problem with them in anything.

heavy ditto on the dizzy mech advance. You can see it with a timing light. Rev the motor to 3000ish and with a worn advance mechanism, you can see the spark scattering all over the place. You can also see sticky advance and vac advance by using the light and alternately slowly and quickly revving the motor.

Not responsible for advice not taken...