try

Is it 100% certain that a Grand Cherokee with a distributor is an 0630 head, no matrer the year? I'm looking at a GC in a wrecking yard with a distributor and I would have to pull the head myself. I don't want to commence work on it unless I can be certain it is an 0630. The engine bay is -mint-, it looks like a good gead. Only ID mark I can find is a large X on the driver's side of the head.

extrashaky

Nothing is 100% certain, because a moron could have swapped in a 0331 for some idiotic reason. (Don't scoff. Inexplicably, it has happened.) However, it's extremely likely it's a 0630.

The head will have the casting number on the top driver's side edge of the deck right near the #4 cylinder (counting from the front). It will probably be partially covered by the valve cover, and it may be difficult to see if there's gunk on it. If you can't see it, you could always pull the valve cover off, and then it should be easy to see:

Bugout4x4

Let me ask you a serious question. Have you seen any of these heads with oversized stepped down valve stems yet? The one I took off mine had these. I have a full set of good low mileage like new valves I will give someone if they are willing to pay just the shipping.