piston to valve contact?

I am going to be doing the head gasket on my 04 sentra in a few weeks, and while the head was off i was thinking of having 20 thousandths taken off to bump the compression a bit. is there any way i can find out if i will run into piston valve contact with out putting the putty shit on the piston and measuring it, the head is a pain in the ass on this car so i am trying to avoid doing it twice.