I ended up fixing the decal mistake, but noticed a bigger issue with the paint on the other shell. I broke out my Badger sand blaster and removed about 95% of the paint. I then used a stiff bristle brush dipped in ELO and scrubbed any remaining areas. This worked well and I already reapplied the first coat of paint without issue.
Thanks for the suggestions.
Jeff, I tried baking soda before but that only clogged the sandblaster. Did you do anything special to prepare it? I was thinking of microwaving the baking soda first to remove moisture.