If the clutch fork is almost hitting the rear of the opening, then the bearing is indeed too short. Fork should be almost hitting the front when correctly installed.
Take out your old throw out bearing for reference and bring it with you to match up bore diameter and where the clutch fork rides (might bring the clutch fork as well).
This is the "long" throw out bearing for a diaphragm style pressure plate (3-finger pressure plate uses a flat faced throw out bearing), and should measure just under 2" depending on what store you use:
You may or may not need the adjustable pivot ball, but it can be used to "fine tune" the throw out bearing/fork. Make sure the pivot ball fits well in the matching "dimple" on the clutch fork. As I recall, the aftermarket generic clutch fork had a smaller than stock dimple and I had to re-shape my pivot ball to get it to fit into the dimple - this should be a sign that you have the generic clutch fork which is not correct and should get the correct Pontiac clutch fork. You should also not be able to go past the throw out collar with the fork arms, if you can, again, aftermarket fork which means it can slip past the throw out bearing and bind.
"I found a short in only one circuit, the brake/courtesy lamp fuse popped so I need to troubleshoot that one,"
PJ: This has come up a couple times. Seems it will turn out to be the courtesy lamp, check the wiring to it and the lamp socket itself.
I enclosed a photo for comparison between long & short throw out bearings. Not the exact one you want, but you can clearly see the comparison. There is an intermediate size as well, but not as common, so it should be the long you need.