Before you pull the head you may want to try a little trick I have used successfully a number of times.  Get yourself an auto side marker bulb or dash light bulb, I have forgotten the number right now but the little push in bulbs and solder on two wires long enough to go to a 12 volt battery.  Tape off base of bulb to avoid shorts. You should be able to now slide into spark plug hole and be able to look around with a light that is now illuminating the combustion chamber from the inside.  Gives a lot better look around.