4A-GE valve shim disintegrated

[Dave W]

If it was my head, I would try to save it. I think after removing the head, I would try to push the lifter a little lower to help in removing the burrs and prevent any more damage to the surface, before grinding on the head. I would use a medium grit stone in a Dremel tool to cut back the aluminum. Fill the lifter bore with a small layer of grease to prevent the grinding dust getting further down, inside the ID. Getting the lifter out is going to be a real PITA. You might be able to use trans ring pliers to remove the lifter, but I would guess that you will probably have to get a nut welded on to the top of the lifter and then used a slide hammer to remove. Carefully polish the lifter bore with 600 wet and dry paper, then clean the complete head several times. I would also use the 600 paper on the camshaft lobe and lightly polish the surface.
Depending on your milage, you might want to consider getting a valve job, since you are already doing 90% of the work.