He probably would not mind at all and while you seek his approval, you can ask him if he wants his name on the revised or new version. Ethically, it would be wise to make an attempt to contact him though.
Isn't IRC about the best place to catch him, anyone?
If you've made a concerted effort to contact him to no avail then somehow recognize him with something like "Original B2B designer unreachable" Just an idea anyway you can use your own words or those LOL