I've had the same problem on my 87', and I'm in the process right now of removing the rotten bulkeads and replacing with new 1/2 hardwood plywood. Really not a hard job overall.
I was very lucky, and surprised to see, that the factory had evidently cut out a circle around the chainplate holes in the deck core, and filled the void with some kind of epoxy, and then drilled the chainplate slits through the epoxy filler, rather than the deck core plywood. I really checked well, and the chainplates slits in the core are okay, and I attribute that to the slits being surrounded and encased in the factory epoxy, and not the normal core plywood in that area. I was expecting some degree of deck core rot, but it wasn't there.
If you ever decide to replace the bulkeads, I'd recommend only using the original bulkheads as a rough tracing outline, and allow an extra 1/4" in oversizing the new ones, and then rough fitting them back in the boat, and doing the final outline shaping with a orbital sander and 80 grit to get the final outline shape and angle - that worked well for me. Also, do not re-drill the the chainplate holes and bulkead mounting bolt holes from the old bulkead as a template, but rather re-fit the new bulkeads in the boat, and then going in and redrilling the chainplate and bulkead holes from inside the boat through the original fiberglass mounting holes and chainplates. It would be easy to find all the holes off a 1/8" from what is needed, if you used the original bulkeads as a hole drilling template I believe. Make sure when you drop the chainplates through the deck, for drilling the bulkead holes, that you get the height right, or I believe you could have problems with the shrouds not having the same tension. I believe I almost made a mistake in that area, but caught it before drilling.
My plan for finishing the bulkeads is to stain them with RIT dye and denatured alcohol, and then paint over with pentrating epoxy and spar varnish. Hopefully that ends up with a rough match of the existing wood color.
As far as the original bulkead molding - it does not appear to be glued on, but rather tacked on with some kind of internal metal brad biscuit arrangement. I had good luck tapping them off with a 2x3 being hit with a hammer, using the bulkhead as a parallel guide for the gentle blows - the molding broke in a few places, but I feel pretty good I can wood glue it back on the new bulkeads without too much trouble. Overall, it doesn't seem to be a bad job at all, just a series of simple steps and you are done.
It will feel good to have everything replaced, and hopefully good for another 30 years. Good luck if you try it.