Okay, here's some better pictures of what I plan to do:
Here's the original '77 emissions schematic:
Here's what I think it needs to look like after I'm done with it:
And here's the isometric view of the factory hose routing:
And here's what I think I need to remove:
And here's what it will look like when I'm done:
So it really cleans up things. I'm hoping it doesn't mess something up. If it does I guess I can always go back. I'll take pictures of what's actually under the hood when I get to it, but actually these diagrams probably show everything clearer. Just notice that I changed the '77 distributor to what I actually have, a '79-'80 dual advance distributor. The outer diaphragm is the secondary diaphragm that is activated by the High Altitude Compensation (HAC) valve and the inner diaphragm is the primary diaphragm. There is some debate on which one works best hooked up when the truck is desmogged, so I'm going to play with it and see.
Here's the schematic for a '79, and it shows the inner diaphragm being connected to the Advance Port on the carb (factory configuration). But if you look at the second one, it shows it the other way around (though it's been modified by Jim C. and is showing a desmogged system). The operation of '79-'80 and '81-'87 distributors is the same, at least as far as vacuum advance is concerned.