In the 1967-68 time period, Ford began to use a plastic that had a mold release agent as part of the raw plastic. I know that the process was fully implemented in 1969 as a general two part epoxy would not stick to the console from a 1969 Fastback I was trying to repair. This applied to the plastic covers that went over the rear quarter window pivots, same scenerio, the epoxy would peel off. For comparison, the process for a 65 or 66 console shell used a spray-on mold release, therefor the shells could use a general two part type epoxy for repairs. For my 1969 problems, I went to a plastics store out here on the left coast, TAP Plastics, explained my problem and they made a special on part plastics "stickum" recomendation that worked. That was many years back and the tube was tossed.
My recomendation is to find a local specialty retail plastic business and see if they can help.
Something else to consider, in a moisture environment, marine epoxy should be used in any case, and marine epoxys are usually not carried in an auto parts store.
Jim