My current students know that after two years of resisting Blake Snyder's "Save the Cat" I finally broke down and bought a copy. Well worth it. Particularly for chapters four and five. My resistance to the book stemmed from the fact that I found it somewhat... there's really no other way to say this, vulgar. It breaks screenwriting down into a method that felt a bit mechanistic and formulaic in my opinion. However, if you're having trouble with structure, frankly there's no better way to go than mechanistic and formulaic.
Unlike the 70 beat outline you're familiar with, Snyder breaks structure down into 40 scenes with 15 specific sections. It's a unique approach that results in a shorter first act and a longer 3rd act than the method I've been teaching. I used his methodology to develop a pitch for my most recent writing assignment and found it incredibly helpful. Still waiting to find out if I got the job.
In these budget conscious times it's even available at the public library. Remember those?