"The Long Ez was designed 40 years ago by Burt..."
Yes. I will just note that in that entire time, no one has successfully deviated much from the Rutan design. Those that have worked off of the Rutan design have been fair composite/aero engineers and often worked with Rutan to make the changes.
I have used glass and carbon and I'm building new bodywork for my formula race car now, all carbon. A composite engineer I am not. All the properties of carbon are not always good when used as a direct replacement for something designed in glass. This is the point I would make. Burt designed in glass and moldless. Taking the same design and trying to replace the glass with carbon is not something to be done by the seat of your pants. One, you'll likely never finish, two - which is probably for the best since you'll more likely than not cause yourself harm.
Put it another way, if you are not capable of designing a canard in carbon from a clean sheet of paper, your are not qualified to substantially modify a Long EZ. if you have that skill level then go for it.