Hi Andy,
Overheating while stopped is not an uncommon problem that has been addressed by most Healey owners. My 67 BJ8 had the same problem although it never climbed above 212 deg. Having higher compression in your new block would generate more heat in the engine which may contribute to why you are now having this problem.
You want to use the correct sleeved thermostat. That will give you faster warm-ups and keep you from running under temp in cool weather. Removing the thermostat may cause it to overheat move since the thermostat slows the coolant circulation to allow it to absorb and dissipate more heat. A six-bladed flex fan will move a lot more air at idle than the stock fan. A larger and more efficient radiator core will do wonders. You may want to consider a coolant recovery system so that the radiator is always full of coolant. More coolant translates to more potential cooling capacity. Redline Water Wetter is a good coolant additive which helps to increase heat transfer.
I used the fan sold by British Car Specialists here in California at the advice of other members and have been very happy with it. I tried a couple of thermostats and found the sleeved thermostat sold by BCS to also function the best. The 165 deg. sleeved thermostat sold by Moss had a tendency to run the engine too cold (145 deg F) when in cold weather. The BCS unit warms the engine up quickly and doesn’t let it drop below 160 deg in cold weather.
With the 4-row radiator, BCS 6-bladed flex fan, BCS sleeved thermostat, and some Redline Water Wetter, my car never climbs above 185 deg when sitting in traffic in 100 deg California weather. Now, that doesn’t mean I don’t overheat while being baked in the 100 deg sun in the open cockpit, but that Healey grin never leaves my face! /bcforum/images/%%GRAEMLIN_URL%%/smile.gif
Mark