This is a tough question, I have a bone stock 72 also that I do not want to cut or modify to a point where it can't be changed back. I do love the sound of my MFI amd sport exaust but I also love music and at least traffic radio updates on the way to or from work.
The stock radio is in it and stock speaker, and it gets maybe one station, of course not one I care to ever listen to. I'm looking to this as a possibility for speaker mounting :
http://www.pelicanparts.com/cgi-bin/ksearch/PEL_search.cgi?command=show_part_page&please_wait=N&make=POR&model=911M§ion=INTacc&page=34&bookmark=60&part_number=PEL-MOCH-2000
I still have not come up with a good plan for the radio, again I want to keep the stock opening but get a radio that an MP3 player could be plugged into.