|Pat, Angus, Geoff and Alan,
Thank you for the informative replies.
I have the original cast iron exhaust manifolds and crab claw filters fitted which I want to retain. Instead of exhaust wrap, I am considering ceramic coating both inside and out of the exhaust manifolds which, I am told moves the radiating heat further back down the exhaust system. I have already covered the firewall, transmission tunnel and floor with fiberglass/foil insulation which helps cool the passenger compartment.
I thought about removing the thermostat all together, but recall information against that as per Geoff's comment- too fast circulation for the radiator to cool. There is a thermostat blanking sleeve used in racing MGB 1800cc's offering less restriction than a thermostat which was recommended. I tried that but the inlet manifold internal casting would not allow it to seat properly. I considered altering the sleeve to make it fit, but abandoned that idea on the basis that that may cause some turbulence and an unwanted hot spot.
I suppose what I am trying to achieve, as we do get icy cold weather here as well, is a year round, one size fits all approach that will not require altering season to season, but it may not be possible owing to our extreme temperature variation, however, I am still searching for "Nirvana" !!
I think my next move will be the BBT which can be supplied with different temp ratings, and Geoff's different, presumably smaller circumference, water pump pulley.
Angus, like you, I cosset my car, my first MG, to my mind, the best, so why change it. We have had this relationship since 1976. 36 years during which time she has not always performed impeccably, but been forgiven. Even my wife of a mere 18 years accepts her and does not resent the time I spend in the garage with my mistress!! Indeed it was Anita's insistence that when we retired to the US that the MG came too.