That is the plan I have right now going forward. You can't see it in the pics, but there is a valve plumbed into the heater line so I can manually turn the water off from going into the heater core. When I was driving the car in High School the vacum controled heater and A/C controls stopped working. My dad and I wired in a switch under the dash to turn on the blower motor so I would have heat and defrost in the cold months and then in the warmer months, I could just turn the water off so the heater core wasn't blowing hot air inside the car. Blasphamy!
I had a '68 Firebird that had a similar issue with the heater control but I plumbed a 1/4-turn ball valve into the line as opposed to a water spicket valve. That does look pretty funny in there.