[Piwoslaw]

It looks like I've found a heater that will fit the heater core plumbing. The only place it will fit is on the hose going from the thermostat up to the cabin, then up again and suddenly straight down to the water pump. When the heating element is plugged in, the heat will rise through the heater core, then to the pump, and only then into the engine block. Will there be any heat left by then?

The heater has it's own t-stat which disconnects it from electricity once it warms to 80*C, so when plugged in it will not be as hot as the hoses during normal engine operation. The maker of the of the heater even states that it can be insulated with with the same foam used on central heating plumbing. Of course this would have to stand temps as high as 120*C, but it would increase the efficiency of the heater.