Hey , it's Uncle Mikey checking in,
I have done lots of core work on dozens of boats, Pearsons, Columbias, C&C's, Southern Cross, etc. and after many hours of the "Big Fun" I use a DeWalt industrial Dremel tool clone ( drywall cutout tool to an electrician ) , I use a bit for cutting ceramic tile , solid carbide .
If I were doing another Ariel foredeck, I would cut the whole thing out at once again ( never lost any camber ) I would stay with Wescore and save and reuse the old deck skin ( it still has the shape )
Just go around the edge of the deck with the cutter.
I use a pre-thickened 1:1 epoxy to bed the core, available from ;

www.fgci.com

Use Shurform tools to work the core down after it is glued in place. Grind the back of the old deck with a 36 grit disk o remove the ridges and gunk . Trowel on some more of the fgci epoxy using a notched (tile-setter's) tool and squish the old deck in place. Fill in the holes and gaps with the epoxy. Grind the whole deck with 36 or 40 grit and lay on some cloth set in epoxy or vinylester resin ( I prefer Vinylester ). Sand it , fill it fair it and sand again . Layout your non-skid pattern ( I like to use Interlux particles in polyurethane primer ), paint it on and finish as you please .

That is it in a nutshell , it is 10% brains and 99% grunt work ( you'll only use 1% of the alotted brain power )

Mike G