getting thermostat out

yes it is a slant 6: he says the housing for the water pump which is connected to the block makes it impossible to get the drill on the lower thermostat bolt. I am thinking of getting an aftermarket electrical gage to hook up so I have a more accurate reading than the stock to keep an eye on the temp. I run a bit hot according to the gage now, so I was flushing the system and changing the thermostat as a preventive measure but don't want to get into puling the head.