Veering off topic, but do they actually test egr operation?
I assume the ~$500 tbi-vortec intakes have external egr provisions, but the valve still resides on the intake. Since the valve isn't doing anything, the "feed" pad for the egr could be left open. As you said, if someone knew exactly what they were looking at they might be able to figure it out, but since tbi and carbs all used crossover to feed the egr, and the valve looks the same, and still sits on the intake, I think it would be hard to tell.
At least on my vortec tpi base the egr "feed pad" is on the passenger rear above #8, and if it is on the tbi-vortec intakes as well, couldn't that be buried under the external coil/bracket? Just thinking out loud...