Sorry Fudd I have no experience with PH, I am drawing my reference on similar types of material I have had the pleasure machining.
With as many holes as you have to do I would suggest getting a high end tooling supplier in and go by their recomendations, they usually put their money where their mouth is and bring samples and actually help you run untill you are happy with the outcome.
If you are drilling rough cast you probably will need to spot the holes but maybe the supplier will tell you otherwise.
The high grade tooling I have readily available here may not be as easy to get where you are at.
Sorry I can't really be of more help.
My offer to run some of these parts still stands (I am kinda slow right now).
__________________
www.integratedmechanical.ca |