Not that I am a wealth of experience but your trials and tribulations seems to be mirroring my problems with my recently aquired truck (and our mechanical knowledge seem to match up, i.e. near non-existant) so here it goes.
Get a new cap, rotor, points, condenser, wires & plugs, that way you can eliminate those relatively cheap parts as the problem. Keep the old ones incase they were good so you will have spares. I'd do the distributor parts first , if no change in performance then change the plugs, again if no change then the wires.
The bushing your refer to is the vacuum advance, it shouldn't have anything to do with your problems as it only comes into play at higher engine speeds.
I also stripped out my brake bleed screw so I went ahead and installed new wheel cylinders, again not too expensive and now I don't have to worry about them. Actually one thing lead to another and I re-did the entire brake system, remember whoa is more important than go!
My biggest advice to you is to find someone with basic mechanical knowledge (these trucks are VERY basic) and make him/her your best buddy. I was adopted my the mechanics here at the plant and have learned sooo much by their hands-on training/advice that is impossible to convey via this board. Buy them lunch, dinner or free health care, what ever deal you can strike but it very difficult and discouraging to try to trouble shoot alone at our level. I couldn't have done what I've done without hands-on help.
I'd be willing to help you later on but right know I'm finishing my truck (new distrbutor and u-joints go on tonight) and if I start spending time under another truck right away I believe SWMBO may not be very happy. Give me a week or two!