I've had my fair amount of internet relationships, and I think sharing my experience may help you!
First off, MOST people you meet online, are pretty honest about their age, sex, and location. (At least, if you meet them on a forum. Meeting them in a chatroom... is more sketchy.) Though, you say you've been chatting with him for a few years. It's terribly rare that you would find a stalker who is that patient (and unlikely to begin with--stalkers are rarer than the media would let on). But have you talked to him over the phone? If not, I suggest doing that for a few months before meeting up.
But when it comes to meeting up with people you met online... I've done it with at least 6 separate people, an uncountable amount of times. And I have more trips to meet people planned. BUT, for your first time ever doing something like this, I recommend bringing a friend along--going to the other side of the country is a long way away, and if things don't work out... well, there's safety in numbers. To be honest though, I doubt you have anything to worry about. Again, talk on the phone to him if you haven't, and do it a lot. Be warned though: Once you meet him in person, it's HARD going back and only being able to talk online.
But convincing your parents seems to be the biggest problem for you, and I don't know how much I can help with that. My dad has never been against my trips to meet e-friends, but he's open minded and modern like that. I wouldn't recommend lying to your parents though, because if something DOES happen, they NEED to know where you are. Since you're over 18 though, it's really your call in the end, as long as you pay for the trip.
But why doesn't he come to see you? That might be easier. That way, you can meet him in a safe place, and then have a better chance of going to visit him next time.