An interesting analysis. I for one appreciate that you included a ratted out Ghia.
It's been pointed out that one exception to the frowning face on macho cars is the AC Cobra with it's guppy mouth.
I'd put the differences in the Spark and Camaro to packaging and expected performance. Difference in the cabin of the two cars isn't all that great. But the engine and tires for higher peformance exact a toll. For the opposite case, continuity across platform sizes, I'd compare the '67 Imapla and Corvair coupe.
In this case I think the smaller car is more successful
For the pouncing animal stance, try moving the front axle forward, in this case 8":
