TEMPERATURE AND GAS GAUGE NOT WORKING-HELP

As the title describes my temperature and gas gauge are not working in my 1963 Plymouth Valiant. Regarding the temperature gauge, I have put a new temp. sending unit in the head, put a NOS temp. gauge in dash, put a new thermostat in, radiator has been reamed and flushed. What else is there? And it still pegs hot on the gauge. I put a radiator cap that reads temp. and it shows 180 as it should with the 180 thermostat. I won't post my problem with the gas gauge but here again I have replaced the sending unit and tested the gas gauge and it shows that it is working but the dash gauge only reads 1/4 tank even when it is full. We have added extra grounds and nothing helps. If someone wants to talk live I am Chet 281-770-2116. I have read everything I can find about these problems and understand about the relationship with voltage regulator but and am about to give up.