I'm probably overthinking this, but because I have the heating capacity, why not heat more coolant...
I thought of using the lower radiator hose as the inlet to the heater and the lower heater core hose as the outlet from the heater, with the supplied "Y". The only reason for using the lower heater core hose, is that it's a shorter run from the upper core hose, to the flange on the rear of the head.
- Feed the heater from the lower rad hose; the thermostat will prevent pulling from the block.
- Heated coolant gets pushed through the core and into the rear of the head.
- Flow continues through the entire head and maybe into the block.
- Heated coolant exits the head, via the upper radiator hose and pump bypass hose.
- Heated coolant is drawn through the radiator and back to the tank heater. I'm only thinking a small residual amount will be pushed through the steel pipe to the heater core.
- From here, the cycle continues.
On a side note I Googled the intake heater grids. Apparently, you'd need some type of control, or manually drop the heater out of the circuit in 15-20 second intervals. It's designed to be like this, otherwise you end up burning your alternator out. These things are a huge amperage draw, and were designed for the cold smoking and emissions, as previously mentioned.
I guess, starting with the GPs and then designing a system to run the grid, will get the engine temperature up faster, getting heat faster. It'd be a lot of work, but it'd be pretty crafty.
-Todd