Assuming you are running an ATI balancer, this one is my favorite. But you need to buy the balancer from him so the triggers will be in the correct location. Notice no crank trigger wheel. I like that.

http://hemimilitia.com/pge2.html

If you like the old way. You can get this from Mancini or Mazzolini.

http://arengineering.com/products/crank-trigger-kit/