Detachable magazine model?
Tap out the magazine catch retaining pin. Remove the mag. catch and its spring. Use an Allen wrench to remove the front trigger guard retaining screw. Don't lose the collar that this screw pases through.
Your PH is basically a modified '98 Mauser. A sporting stock for a '98 can be fitted. It won't be a drop in. There will be inletting required for the trigger group, safety, etc, but it can be done.