Richard, I don't think the gaskets will seal themselves.  Replacing the
gaskets isn't enough, you have to very thoroughly clean the surfaces when you
replace them and be sure that the surfaces aren't too irregular (smooth as
possible).  I spent several hours on the last head gasket job I did just
cleaning out the grooves that the o-rings set in on the tops and bottoms of
the pistons.  Also it is possible that one of the o-rings got snagged upon
putting the head back on and is now partially out of the groove, allowing the
coolant to enter the combustion chamber.

The other possibility is that your head has a crack in it that is allowing
coolant to leak into the exhaust port from the waterjacket (as you shut off
the engine it actually gets hotter.  This could allow a small crack to expand
and then the coolant system pressure could be forcing it out through the
crack).

Either way it sounds like a head removal and pressure testing are in order.
Sorry to be the one to break this to you, but I just don't see a happy
explanation for your problem.