Water heat the intake, you interupt the coolant line going to your heater core.
For non water heated intake manifolds, there are a few tricks people have done. Some use shrouds over the carb/headers. You can find carb spacers, even off ebay, that you can plumb a coolant line too.
As for headers, might wanna contact the major header manufacturers, I tried contacting summit and jegs, they had nothing, that doesnt mean they dont exist.
Good luck
