Just be honest,
It's a Superformance,FFR, Kirkham, fill-in-the-name Cobra. That answer is going to satisfy 75-80% of the people that ask the question, because they have no knowledge of what the originals were.
If you are at a car show, those in the know, will know the maker's name, and appreciate the car, for what it is.
The other 10-15% will keep on puzzling about it, at which point, you can always throw in some technical information, about your fuel or oiling system, to confuse them further.
Some of them may be sufficiently confused as to pretend to understand, what you just said
