I recently found my project truck that I've been searching for the last 2-3
years.  I'm now trying to get everything functioning as it should.  My
current project is the heater.  The truck is a 1972 GMC with a 350 small
block engine, not original and as such none of the factory connections for
heater have been installed.  The truck does not have a/c.  Right now the
heater is not hooked up at all (items under the hood).  I am in need of some
advice on how to do this and the parts necessary.  It may be as simple as
explaining which heater hose connects where, ie. upper line to engine??
lower line to rad??  or vice versa and where / how is the heater control
valve installed??  Any help (pictures, diagrams) would be very helpful.  I
have the Haynes Manual, but it is basically useless in terms of explaining
the heater components.

Thanks!