How much of the heads would need to be milled off th raise cr to 10.5:1 I have new wiseco 9:1 already with andrews b cam.

 

You need to measure the volume of your cylinder (piston up vs piston down) and the volume of your chamber in your heads to find out exactly what your current ratio is. Just because you have 9.5:1 pistons, that doesn't mean your current ratio is 9.5:1. It is most likely lower.
This work is generally done by a proffessional engine builder. Find a good one and stay with him. Most of your Pro Drag Racers own shops and can do this work. There are independent shops that can also do it. I'm not a builder and don't have the facility and equipment to do this kind of work, I have a builder that does this for me.
When you get to shaving heads without valve and piston work, your piston may start banging your valves and spark plug, depending on how much you shave.
Your cam doesn't dictate what your compression ratio is; the cam makes the most of it along with other factors like flow in the heads, carboration and exhaust. It factors in on lift and valve to piston clearance.