1 set of components enough?

[Nova_Cobra64]

I'm working on piecing together a stereo system for my 69 GMC. I want to do more of a sound quality setup, don't care much for blaring loud or too much bass these days (getting old at 26 I guess?). My sister's boyfriend has some unused Focal KRX2 components that he wants to sell cheap. They are still more than I planned to spend, but I know what these things are worth and I might as well help them out. They will be either be in fiberglass kick panels or installed on the bottom of the door in fiberglass enclosures. I'm planning to do either a couple 10" or one 12" Alpine Type R. Sub box/amp rack will be built for the space where the fuel tank used to be, and there should be room for additional speakers as well if needed. What I am curious about is if one set of quality components will be adequate, and if not what would be recommended to accompany them (as well as recommended placement)? Both would be running off the same amp, so the second set of speakers should handle the same power as the Focals (100rms, 2 ohms).