Johndoe - just to say that i think you should contact him too. Whats the worst that can happen, he'll express his anger and then you wont see him again...what's the best that can happen - the two of you can get to know each other and you can be his dad.
I gues it must be a little scary thou, and it will be a bit wierd picking up after so many years. Go into it knowing that you are building a relationship with a man not a boy, a man who has his own ideas, values and who formed those with out you giving guidence so you may not agree with certain things he values but thats something you just have to deal with .. but dude "Strong with you the force it is" ..
may the force be with you bro...