Hi All,   It seems to me that the best way to heat your water cooled Vanagon
after installing a  air cooled Porsche engine is to make a water heat
exchanger around the outside of the muffler and install a belt driven water
pump on the engine to circulate water through the stock water system. To
make the heat exchanger you could start with a long glasspack muffler and
weld a tube around the muffler to create a water jacket. plumb each end of
the water jacket so water will circulate from one end to the other and then
flow through the stock water system of teh Vanagon.  I have thought of doing
the same thing on a Baja bug to eliminate all of the steam inside the car
when it is wet and the heater is on. In a Baja I would have to install a
radiator to cool the water when the heat is off and the heater core is not
dissapating the heat.
Todd Francis