Speaker location 1978 MGB

1978 MGB - I wish to install speakers. I have looked at door panels but space is limited. I would prefer not to cut into the trunk as this year's roof folds down covering the area which would seriously impede speaker quality. I am thinking of mounting through inside fenders below dash on both sides. Does anyone know if there would be a problem cutting into these cavities.
Or have a better suggestion.
Thanks

One of the things covered in the Haynes Restoration Manual MGB 2nd ed is updating the sound system in the MGB. They indicate speakers in the doors in the forward bottom quarter of the doors. Of course, as they indicate in the book, the wiring through the door bulkheads should be protected by grommets. In the upgrade they performed, they accomplished the upgrade to a CD player by mounting a CD changer in the trunk. Upgrading in this fashion allows an up-to-date system without necessitating a change in the console.

Thanks

I had read that manual, however the speakers I had had to much depth. So I ended up building boxes for them and setting them in rear. Then I cut two holes in interior of front fenders for forward speakers. I covered them in plastic to protect them when car is oil sprayed in fall.
Of course when I went to start it up for a drive on the Canada Day the fuel pump stopped working. I love British engineering.