This is not a problem, but you will need a section of an old rod blank. first, carefully cut off the cork pistol grip with a razor knife. Then sand off the old cork and glue. Next, measure and cut a piece of an old blank that will fit inside the rod blank you are trying to fix. Epoxy that section in with 30 minute 2 ton epoxy. Cut that blank piece to desires legth (9-11 inch total length) and put your new grip on.

Oh, and make sure that you rough up the section of then ew blank piece that you are inserting to get a good bond!