Have a 96 ex.....bought it with bad head gasket-had supposedly just had valve job, resurfaced head etc. I could not find a place on the gasket where it had definatedly failed, head checked good for warpage with straight edge.
Got su****ious about the the deck surface of the block and it appeared to have some warpage with fairly crude straight edge. Made a shade tree resurfacing tool for the deck surface in order to do it without removing and tearing down the motor. Piece of granite from counter top sink cut-out.....will be true to .0005"...verify with second piece. Spray adhesive to granite, 120 grit sandpaper carefully applied with no wrinkles and work it like a file over the deck surface of the block being careful to use it uniformly end to end of the block. The piece I used was about 5" by 18"....covered the whole deck surface. Sure enough as soon as I started to use it it indicated where the surface was not true. Couple minutes and the whole deck surface was trued up as eveidenced by sand marks! Don"t forget to plug all holes and water jackets in the block! I used tack rags....slight adhesive to hold any particles.
5,000 miles later all is good! Most granite shops have piles of scrap granite from sink cut-outs....more than happy to give you what you need. Also don"t know why it wouldn"t work on cyl head!

 

Never heard of anyone trying a fix like that... but hey, if it works, go for it! I guess the granite is heavy enough to keep even pressure on the sandpaper, so it can do the job well.

 

Had to read the op post twice, at first was like WTF? then realized AHH.. he use the granite slab as a sanding block.