Young man, that's one fine looking El Camino. I've owned a few of them myself and always regretted it when I sold one.
The idle is a little low to tell what's really going on. Maybe you idled the motor down to hear the cam lope because it doesn't lope with the idle set higher. Am I close to the truth? My best guess would be a flat tappet hydraulic cam something like the Comp cam here.....
http://www.summitracing.com/parts/cc...make/chevrolet
The reason I'm saying that is because I have used this cam many times in an otherwise stock SCR motor and it works really well for a street cam. It had a little rumble to it at a high idle, but if you idled the motor down, it would have a little lope to it like the video you posted.
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