Big Block Gear Drive On A Slant?

Why do some gear drives have only one idler and some have 2 idlers?

Do you have a Parts list for those parts you have used in this install? Obviously, you modified the Top gear to be a one bolt with the drive pin for the Slant 6 cam.
Lastly, I didn't modify the cam gear at all. It's a bolt on swap. I did however, figure that to align the crankshaft properly, the crank gear had to be flipped backwards, so that it would align the teeth correctly. Since I had to remark the gear in any event, that's no big deal.I even get to use the advance bushings that come with the 440 gear kit.