
IMO your going down the wrong route here......and over complicating it.
Your future boost port will be usually open in line with your transfers. Mock the top end up and rotate the crank till the trans are just opening. This is where you want charge to flow through the windows of the piston and start to exit through the boost port. Draw a line on your piston from inside the inlet port. Now you have a reference point.
Now all thats to decide is do you want the windows to start to open in line with the boost port, if so have the hole 'bottom' on the line. Or fully open when the boost starts to open have the hole 'top' on the line. Or anywhere in between.
Boost ports don't tend to flow that much anyway so massive windows are questionable. Why not just cut two round ones, they will be stronger, flow sufficient amounts of gas etc....Like the MB pistons......

What about your inlet port are you modding that at all, apart from the boost port?
Hope that makes sense.
Adam