I run the Intermediate category here, and I've done a 2.5hr HS which ended lasting 3hrs for me.. I'm pretty right hand happy too, and I didn't run out.
So, yes it'll last 2hrs, NO matter how you ride it. And if it's your first race, you'll quickly see that it's not about going flat out...
Advice.. You can't win the race on the first lap, but you can lose the race on the first lap.. So take it easy if you don't get a practice run (we dont' get one here). Don't look back.. No matter what you think you hear, don't look backwards. It totally ruins your focus for what's coming ahead of you. If there's a really fast guy behind you, you'll know it. Block people from passing you early on.. I've found that I can nearly get the hole-shot on my 220R, and if I'm aggressive with my blocking, then nobody is getting by me. (I mean blocking if you have the guy in front of you right there).. Otherwise, let them by, or you'll get shot.
Good luck! Keep the forearms working before the race.. Stay loose, and I'd recommend eating alot of salty homefries with your breakfast that morning.. The sodium and the potassium in the potatoes will help you from cramping. Hold your pee until just before the race, then go.. And drink LOTS of water, don't hold back, or you'll suffer mentally.. Your brain will shut itself off if it's being dehydrated.
Jon!