A body Front speaker location?

I have a set of the kickpanels in my 68 Barracuda. The speakers are a goofy size, like 4 x 6 and are cheap. The key would be to buy the panels without the cheap Chinese speakers and install a quality speaker of your own choice. I`ve seen somebody on Ebay offer them with a better Pioneer speaker. The panels are made of a ABS plastic and are a little thinner than the factory units. Oh , and the fresh air vents will not open fully if you use the kick panel speakers. There are openings in the doors at the bottom front and if you don`t mind trashing your door panels a round speaker (4.5"? maybe) will fit in there and sound very good.