I get around this by hand lapping the piston to the bore...of course this is for larger 2-strokes (>125 cc). This is subsequent to oversizing the bore and using a clearance of 0.03 mm (for a 50 to 58 mm bore). The final clearance comes to between 0.05 and 0.06 mm. With this setting there is light rattling of the piston when the engine is cold but this disappears once it warms up.

In my opinion the taper of the piston (i.e., its cylindricity) is more important than its cam. You can get the same effect as a cam-ground piston for a fraction of the cost by hand-lapping. Usually a cylindricity of 0.01 to 0.02 is desirable.