According to the 81 to 86 manual you should probably have a seperate cooler as well as the radiator one.
Ordered me one of those infra red thermometers and it arrived today. Interesting. The ambient temperature in my bedroom is 24ºCMy skin is 29, and Dwezil is about 27. I thought I'd be warmer than that Maybe I'm part Lizard?
Personally I would say if your cooling system was working correctly, unless you were raging it about by the scruff of the neck on a really hot days like we might have two a year, it should be able to cope. first thing I would do is start again, rad off and flushed out both ways, change thermostat , waterpump and remove all pipes to check were each pipe attaches too has not semi blocked up causing reduced flow, take pipes off heater matrix at bulkhead and flush this out both ways, if your water system flows through you inlet manifold check this for blockages too, once you are happy everything is clear, put together and fill with water only, make sure you have no airlocks, some engines are a swine for air locks. you can then fill system with water only and run up to temp and make sure you heaters are on hot, you dont need heater fan running, measure everything with your temp sensor, once thermostat opens after a few minutes you should have a rad equally hot from top to bottom by touch and no cold spots or pipes, flex pipes and move them up and down if you suspect air lock. Once your happy with temp and stable, you can drain and refill with water/coolant, after all no point keep chucking coolant on the floor everytime you remove a hose.