Well, another knowledgeable person has posted on my “help me” thread on the Gemini forums. Seems that I might be able to completely avoid using one of the coolant chambers on the manifold - the one designed to provide heating for the runners, and feeds to heat the throttle body - which I don’t need anyway. Means I can just run a pipe from the bottom of the thermostat housing through to the heater, and that’s that. The coolant temp sender isn’t changed, and if I do need a coolant feed for a turbo or something down the track, then I can open up that chamber again and spend the money to modify it to allow for the heater pipes *shrugs*