two questions

hey guys...my temperature gauge inside my car doesnt work properly...i was looking at my thermostat and seen what may be the plug for my temp sensor...ok its an '88, orginally had a 305 TBI, i just had a carb 350 dropped in...where is my temp sensor located??? and also...the 305 was a single cat exhaust system...i want to put dual exhaust on the 350, do i have to relocate my gas lines and such??
any help would be most appreciative,
luke