Its hard to say what you are seeing. If bulkheads are tabbed properly they float on the hull, if they are attached directly they can cause hard spots and some curving in the hull would not be unusual after 30 years.
But as to buckling and splitting, if you mean in the fiberglass, that needs to be ground away and rebuilt and refinished if it has split fibers. On the wood bulkheads, if there is no visible damage there probably is no damqage. Look to see if they have shifted at joints or behind decorative moldings, look to see if the chainplates have shifted or the bolts in them pulled sideways in their holes. See if any doors and drawers close properly, or bind, indicating a distortion in the shape.
If you are not familiar with this stuff, it probably pays to have a surveyor come out and make your sale arrangements "pending sea trial and survey" to make sure a pro doesn't find other damages you might not notice. If the boat is so cheap it isn't worth the price of a survey...well, that's possible too, just remember that repairs or disposal can cost more than a boat does!