I made a few discoveries while checking on runtimes and whatnot:
1. The list was actually 398 titles, not 403.
2. I'd forgotten to add the six titles I hadn't seen in The Best of Abbott and Costello Vol. 3.
3. I'd forgotten (possibly consciously) to add Waterworld.
4. I'd accidentally added a number of direct-to-video releases to the list.
5. I had enough Hitchcock movies on the list to comprise an entire month's viewing.
With all of that in mind, I shifted all of the Hitchcock films into August (The Master's month of birth), added the Abbott and Costello and the Costner, and removed the direct-to-video movies.
The end result is that the list is now at an even 400 movies. MUCH better for mathy purposes.