are these good compression readings?
 

Just ran a dry compression test after warming up the engine (trying to troubleshoot why it idles a little rough)
1990 F350 7.5L (460) FI

Are these considered good readings?

Cylinder
1: 140
2: 139
3: 140
4: 139
5: 140
6: 145
7: 145
8: 150

Those all look good to me. You can check the rings by putting a small amount of oil in each cylinder through the spark plug and recheck compression. If it shoots up the rings are worn.

You are well within the 10% variance that is considered good and those numbers are pretty decent for a stock engine.

As it turns out the problem wasn't the engine misfiring causing the vibration, it was the fan clutch that had gone out and the fan was vibrating heavily because it was not centered anymore due to the clutch being messed up. Picked up a new fan clutch from Autozone for $35 and the problem is solved. Runs perfect.

How many miles are on your truck?

106,957 miles