My name is Dale.
There is not much information available for your Fiat. I did find this information that may help you get the cams lined up.
Take a look and see if this helps.
There are two versions of the Fiat Twin-Cam engine-early and late. The early models lasted up till about 1973 and then they were replaced in 1974 by the late version of the motor. The early engine has the distributor mounted low on the block on the left-hand (driver's) side. Later engines (known as the 132 series) have the distributor mounted high on the block next the right-hand cam cover. Although the procedure for both of these engines is essentially the same, Fiat altered the procedure slightly when they changed to the later engines.
On late-model twin cam engines, when the hole in the cam gear is aligned with the fixed pointer, the timing marks should be on TDC as shown
Disconnect the negative battery terminal.
Remove the air cleaner and the heated air hose.
Remove all drive belts.
Drain the cooling system.
Remove the hoses from the controlled bypass thermostat.
Remove the hoses from the radiator and the union from the timing cover.
Remove the timing cover bolts and the cover.
Remove the crankshaft pulley bolt and the pulley.
Remove the lower timing belt cover.
Remove the dipstick tube bracket and the tube.
Loosen the belt tensioner.
Pry the pulley to release the belt tension.
Tighten the belt tensioner to hold the belt slack.
Remove the timing belt.
Do not reuse the timing belt. Do not remove the tensioner spring retaining bolt.
Remove the rear timing belt cover.
Remove the fuel return line, fuel vent line, air conditioning fast idle hose, and the electrical connection from the idle shutoff solenoid valve.
Early twin-cam engine showing fixed pointer for valve timing. There should be small holes or punch marks in the cam gears. Although you can see an A and an S in this illustration, it's unlikely you will find them on your cam gears
Remove the blue and white stripe lines from the electrovalve and the black line from the gulp valve.
Disconnect the gulp valve air hose and the power brake vacuum hose.
Disconnect the fuel line from the carburetor.
Disconnect the accelerator rod and its linkage.
Remove the hot water hoses from the choke housing.
On cars with air conditioning, disconnect the reservoir vacuum hose from the intake manifold.
On cars with air conditioning disconnect the steel vacuum line from the intake manifold.
Disconnect the coil wire and the spark plug wires.
To make reinstallation easier mark each spark plug wire with its cylinder number.
Remove all electrical connections from the distributor.
Belt tightening procedure on the early twin-cam engines
Disconnect the temperature sensor wire.
Remove the air pump injection hose from the check valve, if so equipped.
Disconnect the exhaust pipe from the manifold.
On cars with automatic transmissions remove the dipstick bracket and the tube.
Remove the heater hose from the cylinder head.
Remove the heater tube from the exhaust manifold.
Remove the cylinder head bolts and the head.
Installation is the reverse of removal.
Always use new gaskets when reinstalling the heads.
The Flat recommended procedure for timing belt tightening on the early models is to attach a spring scale to the upper right arm of the drive belt idler pulley. Apply a load of sixty pounds to the belt and tighten the idler pulley attaching nut. On the later engines, allow the tensioner to remove the play from the belt. Check the belt tension again after cranking the engine a couple times. Adjust if necessary.
This procedure applies to later engines which have the distributor mounted high on the right-hand cam cover. Before dismantling anything, turn the engine over by hand until no. 4 cylinder is on TDC and the timing mark on the crank pulley is aligned with the TDC mark on the timing cover. The rotor should be pointing at no. 4 in the distributor cap.
At this point, you should be able to see that the holes in the cam pulleys are aligned with the small cast fingers on the cam housing, and the hole in the auxiliary shaft pulley is aligned with the tensioner pulley bolt.
Remove the air cleaner.
Remove the spark plugs.
Remove all the drive belts.
Remove the heater air hose.
Partially drain the cooling system.
Remove the union from the timing belt cover and tie it out of the way.
Remove the timing belt cover.
Remove the water pump pulley bolts and the pulley.
On the late twin-cam engines, the holes in the cam gears should be aligned with the marks on the camshaft housings
Valve timing arrangement for the early twin-cam engines. The A and the S may or may not be marked on your gears. Line the fixed pointer up with the holes or punch marks on the cam gears
Remove the crankshaft pulley nut and the pulley.
Loosen the belt tensioner bracket.
Tighten the bolt to hold the belt slack.
Remove the belt.
Turn the auxiliary shaft-sprocket to align the hole in the sprocket with the sprocket bolt and the spring retaining bolt.
Install the new timing belt. Allow the tensioner to remove the play from the belt.
Turn the crankshaft two full turns. Check that the timing is correct, then tighten the tensioner bracket bolts.
Timing belts cannot be reused. Anytime that the belt tension is relieved, the timing belt must be replaced. The belt should be replaced every 25,000 miles.
Install the timing cover loosely to check timing mark alignment