[C320-list] cabin top leak/removing balsa core

[wdoc1 at aol.com]

Shipmates-
I re-bedded the plate for the starboard mainsheet turning block mid-season last summer after identifying that as the source of a recurring leak. Now need to open the area up and clean out the underlying balsa core which appears to have rotted as evidenced by a subtle 3 inch area of depression of the deck. 
My plan is to use a hole saw to remove the topside fiberglass under the plate, then attempt to get all the wet balsa out, let the area dry over the winter, then fill the void with thickened epoxy. Should I cut a hole in the interior headliner as well?
I welcome all ideas/suggestions.  
Thank you in advance!
Bill McConnell2000 C320 DIVERSION