Job 1: fix the Killer Dowel Pin
Job 2: install those gauges
Reasonable people can differ on the order in which you might do all the rest. My own path emphasized FIRST fixing everything that was broken, about to break, or dreadfully engineered, including:
* Change every fluid, and install Mag-Hytech diff and transmission covers while you're at it
* Replace worn-out shocks with Bilsteins... holy cow what a difference!!!
* Get those leaking batteries out of there before they eat all your lines, scrub everything in sight with baking soda to neutralize the acid, and install Optimas
* Slap a set of LarryB contacts into the starter
* Track down leaks... for me this involved replacing all the transmission cooler lines to lose the unreliable quick-disconnects
* Get everything adjusted properly in the 'Axis of Evil': the throttle linkage, the throttle position sensor (TPS), and the throttle valve cable (I'm assuming you've got an auto).
* If you have any boost leaks, track 'em down and fix 'em.
* Carefully inspect your hitch. Is it cracked? Horribly rusted? Do you trust it?
* Is your carpet wet? Track down cab leaks (third brake light gasket, doors, rear window, etc.
Now take some time to collect some baseline data... MPG for city, hwy, towing, empty; EGTs and boost pressure under various conditions. Having this baseline data will help you judge the effects of your mods.
Only then, once I'd convinced myself the Beast was now road-worthy and I knew what to expect of her, did I start on performance mods. Again, there are any number of paths depending upon your philosophy, your budget, and what you're shooting for. My path is/was:
* #6 TST plate (this is a more conservative choice than many others would recommend)
* Throw away the stock air filter box and install an aFe or other big-honker
* Replace 160HP injectors with 215s
* Advance timing to 15 degrees
* Coming soon: slap on a DSS to address the sloppy steering
* Someday: upgrade the torque converter and valve body