By the title of the post you are thinking that I have lost my dam mind.
I give you an actual living breathing, rainbow farting natural birth unicorn (not some Frankenstein's monster).
This is how I will do it.
Take a plain old 4 barrel edelbrock 650 carburetor that I already have, know how to tune and rebuild, then put it on top of an obsolete 1960s carburetor hot plate and hook coolant lines up to it.
Done.
I have invented nothing new and I am not trying anything that has not been done before.
Of course I am not going to make it that simple I am thinking I will band saw off the 5/8'' heater hose nipples, thread them for 1/4 or 3/8 NPT and install 3/8 hose barbs, because I just don't want big gaudy 5/8 heater hoses running all over the place. Then add a control solenoid to turn off the coolant when I don't need it.
I have seen these before, I just have not seen one in a very long time.
I don't think its actually going to help fuel economy that much unless its nice and chilly. It will help cold starting since I have coolant heater, can circulate coolant through the carb hot plate with the electric coolant pump I already run and I can fill the fuel bowl with my electric fuel pump.
This wont be a big MPG booster, its more of a cold weather contingency plan and tuning aid since I run a edelbrock air gap intake manifold.