On a standard 62 +4 with a TR motor the cooling system is really pretty straight forward and didn't normally have any major overheating issues.
Basically the thermostat housing has the top hose for the rad and a bypass hose to the water pump where the bottom hose also comes in from the bottom of the rad. On the back of the water pump housing is the return from the heater.
The heater is fed from a screw in valve on the top of the cylinder head (available at Melvyn Rutters).
That is the simple standard system . It should be fine with the 7lb cap on the rad and an overflow pipe from just below the cap. The heater obviously needs a repair.
The mod to have the expansion tank requires you to lead the overflow pipe from the rad to the body of the Exp tank and also have an overflow from that tank to waste. The pressure cap then goes on the expansion tank and the sealing cap on the radiator.
If there is still major overheating after that then either the rad is blocked, thermostat stuck closed or water pump knackered.
Sorry I don't have any pictures but there are pictures of engine compartments on the web in for sale ads.
Cheers
