2) Hire him on a contract basis for a month or two. Pay him what you'd pay a senior dev of whatever age. Evaluate him on the progress of the product, and have a trusted external party audit his work (if you yourself aren't technical enough).
3) Stop thinking about discriminating on the basis of age.
If he has been developing so many years, why instead believe in his words why don't test him doing a more technical (hands-on) oriented interview instead a "normal" (talking and such) interview?
Well, IMHO, I think that in such scenario he can shine or fail according if he's saying the truth.
