I have removed my thermostat to use a cool down system for grass drags and asphalt racing.  You will need to find a washer that has the same outsid diameter as the thermostat to put the rubber seal back between the engine and thermostat housing.  I also take a 1/4 -20 carriage bolt, with 2 nuts and a washer, measure the exact distance from the bypass hole to the inner cover face of the thermostat cover, get the distances set, lock down the nuts and then round off the edges of the nut that will set in the bypass hole.  Works great for us, and will flow more coolant than pining the thermostat open.