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OK, in that case bust the surround loose and rebond it where it needs to be. It might seem like a lot of work, but I think you'll find it is actually quicker than to try adding filler.
zwede: I bought the car from Mike Flash, owner of Corvette Specialists here in Beaumont. My shop is just down the road from mine and he dropped by and showed us how to break the bond just as you suggested. We used a narrow metal putty knife like a chisel along the joint to break bond.
We made a tiny wedge from a small piece of a paint mixing stick. By adjusting the depth of the wedge into the crack of the separated bond we got the fender panel tip to lift up and align quite nicely with the edge of the door. Mike gave us the tail-end of a tube of Automix 8243 SMC/Fiberglass Repair adhesive to fill the gap. Now it will be better than new.