Temp & oil pressure Check.

FIRST THING I WOULD DO, IS MAKE SURE THAT BOTH RADIATER FANS ARE RUNNING! IF THEY AREN'T, MAKE THEM, EVEN IF YOU HAVE TO "SHORT" THE GROUND SIDE OF THE RELAY TO GROUND! I DID AWAY WITH MY RELAYS, AND WIRED DIRECT A LONG TIME AGO, JUST BECAUSE THE SENSERS ARE UNRELIABLE! SECOND, YOU SHOULD HAVE A 50/50 MIX OF WATER TO PRESTONE "ANTIBOIL" IN THE COOLING SYSTEM. THIS WILL RAISE THE TEMP. AT WHICH THE MIXTURE WILL BOIL. THIRD, I DOUBLE CLAMPED ALL HOSE CONNECTIONS, ANY LOSS OF COOLANT PRESSURE, NO MATTER HOW MINUTE, WILL RESULT IN OVERHEATING; AS IT LOWERS THE TEMP. AT WHICH A SOLUTION CAN BOIL! FOURTH, IF THE SENDER IS MOUNTED IN THE OVERFLOW TANK, MOVE IT TO THE FRONT OF THE ENGINE BLOCK, WHERE IT BELONGS. FIFTH, AT AN OUTSIDE TEMP. OF 90-100 DEGREES, 190-200 DEGREES ON THE GAUGE IS A NORMAL READING. SIXTH, YOU CAN "TEST" THE GAUGE, AND SENDER, BY DISCONNECTING THE WIRE AT THE SENDER, NOTE READING. THEN GROUND THE WIRE AND NOTE THE READING, THE GAUGE SHOULD BE AT THE MAXIMUM. IF YOU NEED A NEW SENDER (I DID) YOU CAN BY THEM AT NAPA AUTO PARTS FOR $6. SEVENTH, AND LASTLY, IF YOUR CAR IS AN EARLY '72 IT WILL HAVE THE BADLY DESIGNED RADIATER BAFFLE THAT HINDERS PROPER COOLING! THEY REDESIGNED AND FIXED THEM IN LATE '72-73. IF THIS IS THE CASE, YOU WILL CONTINUE TO OVERHEAT, NO MATTER WHAT YOU DO, UNTIL YOU UPGRADE TO AN AFTERMARKET RADIATER. GOING TO A PAIR OF "SUPER" COOLING FANS MAY WORK IN YOUR FAVER! GOOD-LUCK AND BEST REGARDS, MARLIN.

Congratulations. With a few updates, you'll have a very fast, showy & dependable sports car. First, either change ALL the hoses in the car, both cooling and fuel, or verify that the previous owner did this recently. There are 2 short heater hoses under the dash that have been known to rupture while driving, resulting in crashes. Todays gas additives tend to harden old fuel lines, then vibration cracks them, resulting in engine fires.
As for your gauge question, you are correct- if its not spitting coolant out, its not hot, regardless of what the gauge says. Ford determined that a resistor in the gauge line was necessary to make the Italian temp gauge work somewhere near correct with the US-made sender. Two resistors were used at various times: a 5 ohm 1/2 watt, and a 10 ohm 1/2 watt. Try both- Radio Shack has them. Alternatively, a new gauge was offered in early '73 that needed no resistor and reads to 260 degrees. It is a drop-in replacement and, on my car, was accurate with a new Pep Boys sender. The upholstered panel behind the seats comes out, exposing a steel access cover to the front of the engine. This makes belt changing etc easy. The water temp sender (p/n TS-58) should be moved to just below the thermostat in the block, horizontally mounted. The original wire will stretch to fit. Do not believe the oil pressure gauge, either. The same problem occurs re gauge & sender mismatch- any 351C showing 30psi oil pressure while driving would be ready for new bearings! 60 psi is desirable; you can check this with a tee fitting on the rear of the block for a cheap mechanical oil pressure gauge along with the stock sender.