I just did my P/S gear. If the top of that has been open, I certainly would consider tearing it down to clean and re seal it. Mine was totally gross inside, and it was sealed. If you buy that valve, you should tear it down to clean as there is a spool valve inside.
The FSM walks you through the tear down and re-assembly. Rock auto has a Gates kit that has most of the seals and O rings you'll need to do the job. It's pretty straight forward. The only tricky part is setting the inside bearing pre-load, but you can do it with a digital fish scale and some patience.
BTW....That B body valve LOOKS like the one that was on my A body box.