You should be careful with cutting boost-ports. They may look simple, but the theory behind them is complex.
They work by directing a charge of fresh fuel over the top of the piston, to the top of the cylinder after the exhaust port opens and just before the transfers open. This way they force the remaining exhaustgasses out.
They need to be timed and directed well. Take a look at a cylinder with boostports. The ) shape is used to create a sort of venturi effect. The piston comes down, compressing the fuel into the port and then when the port opens it shoots it out, aimed at the top of the cylinder. Aim too low and you will blow fuel out of the exhaustport (Not a big problem, just a waste of fuel), aim too high and you will foul plugs like crazy.
And take care to mark the piston position in BDC through your intake, so your boostwindows will not show. If the windows show through the intake, your bike will run like crap.