From the factory, you could get stereo speakers in the kick panels. A 4x6 will fit, but you may want to find some that aren't deep. I installed Kicker 4x6's and experience popping at higher volumes. BTW, they do reproduce the factory 4x6 speaker grill for the kick panels. Also, I think I've seen custom panels somewhere. I think they allow a 5" or 6" round speaker to be installed.

The problem with the after market dash units is they are made for the '67-8. They will fit the '69 app, but, you have to cut the dash bezel. It's not much, you just have to cut the bar that divides the radio dial face from the push buttons.

I'll get some pics of my stereo install latter today for ya.