First go around I had the kick panel speakers.
They sounded very crappy, and not really much sound quality from blasting your feet.
SO change of plans.
I got a really good quality, smaller, front speaker and mounted it in the door . with a small custom enclosure. All behind the stock deluxe lower grille.Then made a x-over. I mounted the tweeters, on a special bracket hidden up behind the headliner, directed at the two front seats.
Carefully drilled 10 million small holes in the FB quarters, and mounted 2 - 6 x 9's. Everything looks stock and hidden. Added a decent power amp to these speakers, then a 12" sub in the trunk with a good amp.
The system sounds awesome.
Until I start the engine, then I can't hear a d@mn thing, unless I really crank it.
I also found the kick panel speakers really got in the way of your feet in the footwell.
However, I did see a nice installation on a 69-70 where a VMF member made a custom enclosure within the sheet metal of the kick space, by enlarging the sheet metal behind the fender. IN this way, the kick panel is still flat. A really good idea. I wish I tried that.