If you are really worried you could always go one step furthur - why not have something like a heater tap (but bigger) etc that you could turn flow to the auxillary radiator on / off.

Personally if I were to go that route I would be looking at a radiator off a water cooled motor bike - something that is designed to really cool the water.

My 2c. As said by brett, I would rather have a rod cleaned aussie radiator like new than a second auxillary radiator floating around under the bonnet.

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"In two years time your car will be like a lady's clothes, out of date, my car will still be in fashion when I am dead" - Sir Alec speaking to Pininfarina

Also agree about getting your radiator serviced,having done all that I still had a concern with high temp running,mainly multiple traffic lights in summer. In this pic you can see the Clubman heater core that I have used,made up brackets and used Commodore air cleaner rubber mounts.I'm also using Redline Waterwetter and Inhibitor.
It works well

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thanks everyone for your input,

i am going to get the radiator recored, am also getting the temp gauge rebuilt, as the car has come with the capillary tube missing from it, then i'll monitor things and if needed bung in the extra radiator.

i like the watercooled motorbike radiator idea, pity i got rid of the old wreck of a kwaka klr recently!

while i'm here,

it's a 1275 with a weber, how many cores? 2, 3, or 4 when i get the radiator done? from what i've read i'm leaning towards 2 core?

any suggestions? i don't really want to have to modify too much in the way of support panels and inner guards.

Just stick with the standard aussie 3 (???) core one. Our radiators at 16 gills / inch were way ahead of those standard pommy radiators.

You can go to an aftermarket one if you wish, which will give you better cooling but a re-cored aussie one should be good enough IMHO.

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"In two years time your car will be like a lady's clothes, out of date, my car will still be in fashion when I am dead" - Sir Alec speaking to Pininfarina