Mounting Front Speakers

Have you looked at using the dual 3.5" speaker bracket here
It mounts in the place of the original in-dash speaker...

Pulling the factory speaker on your 65 barracuda should be similar to my 64 valiant (assuming no AC)..
-remove the radio
-might need to disconnect one or both heater hoses
-might need to unscrew the fuse box
-i removed the heater control on the dashboard (pull the knob as far as it goes and use needle nose pliers to turn the 'star pattern' piece, that releases it from the front of the dash), unplug the harness on the backside.
-speaker should be accessible, just need to remove 2 nuts that mount it.