My dash guage works, but has not gradiants on it. I've thought about ploting it out but never got aroud to it. My aftermarket guage sensor in the factory spot in the block near the themostat housing. I ended up wiring up the dash one in a taped port on the radiator (Not particually accurate, but does give feedback as to whats going on). I think an emissions switch went here. What year head do you have? I think the later ones also had a taped port for an emissions vacuum switch near the thermostat housing. There's a NPT plug in the water jacket I think near cylc 5 & 6, but I reall reading that using a sensor there reads kinda low. I've also seen an "extension housing" that would allow you to put another sensor at the thermostat housing.