https://brainwalletx.github.io/#generatorjust insert your guesses into the passphrase field that it will convert to an address.

I feel close. I have a solution that matches the right criteria, with the double meaning implied by the question. Just need to figure out how to process it.
Thanks - BitAddress does the same if you enter a non-valid private key. I've been using that.
It's not clear from the question whether the solution to the riddle is the private key itself, or whether it points to the private key. I don't think it will make too much difference either way but would help - knowing if the answer is 32 letters or not would be useful.