Check out the date on the first post. This is possibly the most-resurrected thread on ENW
You're going to run into a few issues with only 2 players.
First, you're going to have the same people making a *lot* of pulls, which I think would get kind of repetitive, and if one player consistently chickens out, the game could stall. With more players, it's a little easier to spread the danger so it creeps up on them, and any one person doesn't feel put upon.
Second, once the tower falls, the game is apt to get kind of linear (and exacerbate issue #1), and your chance of a premature TPK goes way, way up.
Third, a lot of the joy in a good Dread game comes from the interactions of the characters, and the way those interactions can change the course of the game. Fewer players cuts down on that pretty dramatically. It might enhance the tension, since there's little respite, but it also cuts down on being able to do cliffhangers, etc.
To counteract some of those, I'd be tempted to go with some sort of closed-environment survival game, ala The Thing, or Alien, etc. Exploration and resource-management can give you some filler scenes to keep the roller-coaster of lulls and terror going.
Consider ahead of time ways to use 'dead man walking' to keep the first player to 'die' in the game in a meaningful way for as long as possible. Maybe also consider using one of the various 'freebie' optional rules that gives a player a way to buy off a pull a couple times, so if the pacing is off and the tower gets rickety too soon, you can buy some time to get to the good stuff before someone dies.
You might also want to take a look at Fiasco, which is another very rules-light RPG that is GM-less, is exceptionally playable with 3 people, and is an excellent 'gateway RPG' for introducing new players to the hobby.