So I just finished trimming the JBL speaker(s) again.... besides the areas I initially Dremeled out (outlined in GREEN) I now just finished removing the raised lip area (outlined in RED) by bending it down lightly with pliers, and using tin snips to remove it. This was the area of the speaker's outer metal ring that was keeping the main instrument console cover from seating properly:
(Original picture below borrowed)
Now the main instrument console cover fits CORRECTLY and without any gaps. Just how I like it.