Since I don't even know what they look like and I was told they don't make them anymore, Where can I get the heater core clips? Thats the final piece I need to get some heat/defrost in my '67. Any pics of the core sitting in the inner box would be really helpful also :)

They are a 2 'u' square shaped bolts made out of strips of steel about 5mm wide.
in each end is a tapped hole that a small screw goes thu a hole in the back.
They mount at each end of the core over the header tanks.
Not hard to make/bend up out of a couple strips of panel steel, and using a couple long self tapping screws to hold in place.

The reason they do not make the clips anymore.... probably is because it costs the company more to produce them, then they are worth. You can easily make some clips out of some thin gauge sheet metal. Like Steptoe said, the clips are a square "U" shape with two holes drilled into them.