WDZ,
Why do I ask ... just a matter of curiosity more than anything else.
I have some printed literature from Superformance for their GT40R program and in that they advertise a H-M Competition 289 motor, which is actually a Boss 302, as noted in their on line motor spec (see below).
http://gt40racing.com/racing/Engines.html
I know these motors are primarily intended as a race / high performance street motor for the GT-40, but would imagine that one of these might show in a Cobra at some point. For my project, it's probably not the best choice, just wondering if anyone out there has put one into a Cobra. Based on the response so far, they answer is no and in reality, not very likely.