Pressure issues for converting berdan to boxer primers
 

I have turned Greener Police 14 gauge hulls down to correct rim thickness and diameter to shoot. My questions are as follows:
1. After removing the anvil in the Berdan cases, will the extra holes create too much pressure with the 209 primers for low pressure loads (Greendot powder)
2. How hard would it be to find Berdan medium 5 mm primers or is that a viable option.
3. Could the anvil be flattened with inside support to cover the two flash holes and the center hole redrilled for the boxer primers.
Any help would be appreciated.

Tom