My plastic Swanson speed square has a level built in so I don't need to carry a torpedo level anymore. You have to check these out in the store- most of the levels in these are very badly off. I also use it to push crown molding up in the corners to tighten the joint before nailing. You can tap on it to help here. Once you've got your pitch cut right, look at the degree scale and use that to align your cut- it's more accurate than guessing at an 8 1/2 pitch which isn't marked. The large sized ones make excellent saw guides for square cuts too.

I just wish someone would make one with the level in it out of metal- plastic breaks far too easily