Hi Sean,

It might be worth checking the orientation of the distributor gear drive (see http://www.intelab.com/swem/Volvo%20Ignition%20from%20Scratch.htm). However, if that was significantly out them I doubt if you'd be able to start the car at all. You can advance the timing until the engine pings under load - assuming that you get a chance to test this before overheating. Adjusting the timing in either direction will give you a rough idle after a certain point as the engine starts to misfire. If you can advance it significantly without this happening then the timing might well be way out.

When you start the engine from cold, the temp needle should gradually rise past the mid point to about the 3/4 point and then drop back to normal or slightly below as the thermostat opens. If it doesn't do that then think more about the thermostat(s)/water pump/radiator.

Its worth checking the water pump pulley for play and untoward noises.

The fuel mixture can be judged by the colour of the plug ends - you probably need new plugs to check this properly at this stage if the present ones are fouled. If they're fouled with oil and your PCV pipes are clear then its not looking good and may well be worn bores. You could try compression testing the engine to give you a rough idea of the state of the bores/valves.

Its easy to forget to set the heater to 'hot' before filling the cooling system. An airlock there will cause rapid overheating.

How's the oil pressure? Does the oil pressure light come on at idle?

Aidan
--
1967 131, 1969 131, 1973 Triumph GT6