This table looks to be an early Gold Crown I. I know this, as the head rail had the acrylic nameplate (now missing). In two of the photos, you can see that the formica has a wood grain pattern. They are NOT black, as some posters have suggested.
The pockets have been tightened dramatically. Hard to say, from these photos, which method was used to tighten the pockets, but the work doesn't look bad (at least from these photos).
Things to check:
Look at the underside of the slate. Might be hard to tell the color, but if it is actually slate, it will be a bluish gray. If it is Brunstone, it will be brownish gray, and will usually have a "BS" marking on the underside of each piece. Also check for cracks in the slate/Brunstone.
Brunstone is much more difficult to set up, and has a number of issues. When set up properly, you won't likely notice the difference.
Check the condition of the pockets, and ensure that the mounting screws are properly installed, and there aren't any broken off in the pocket castings.
Check the condition of the wood, and ensure that there are no broken or split pieces. Some repairs are not difficult, but some can be a pain. That said, check out the ball box, and the mounting hardware.
Measure the nose height of the cushions, and ensure that they are 1 7/16". Also, check the color of the rail cloth, along the length of the cushions. If it is slightly brown, along the cushion, you can bet that the table has the original Monarch rubber.
Feel along the top side of the cushions. If there is a distinct ridge along the top side of the rail, where the cushion attaches, you can bet that someone installed K66 cushions. Though, the table should have K55 cushions.
You could also measure the distance from the cushion nose to the formica. It should measure 2". However, If someone replaced the original cushions with K55, and didn't modify the sub-rail, it will measure 2 1/8". Not the end of the world, but might be good to know. If the cushions were replaced with K66, the dimension will measure 2", though you may feel the ridge that I mentioned previously.