Suggestions/help with new system

[07SSSC]

I'd like to get your ideas/suggestions/help for my soon to be new system in my '69 C/10. Come warmer weather I'm gonna finally get rid of my 2 Radio Shack "Bass Reflex" (read:junk) speakers and upgrade. Also I'm going to put a fuel cell under the bed and install seats out of an 02ish Silverado including the center folding seat/console. So room won't neccessarily be an issue. I want to do speakers (5.25") in kick panel enclosures and 6x9s behind the seats, maybe a sub, not sure yet. I already have a Panasonic deck in the glovebox. I have a couple of amps sitting around that I bought off a friend before he moved, don't remember what they are rated at though, also bought a Pioneer Premier deck from him. I'm perfectly capabale of doing an install, I just never have, I'm a GM Tech turned GM parts guy so I've got the knowledge. I have installed decks and speakers before but never amps nor a really good full system.

I do plan on spending part of my taxes on this so the funds shouldn't be too big of a concern. I want good speakers, no cheapo 29.95 specials, I figure I may as well do it up right. I prefer sound quality over quantity but you all know how loud it can get in these old trucks goin down the road so keep that in mind. My music of choice is hard rock/metal with the occasional soft stuff (doo wop, acapella, soft rock, etc.) mixed in for good measure.

So, questions are-
What brand/type of speakers do you recommend and where should I buy them?
Should I custom build box(es) for behind the seat, and furthermore, 1 box to house everything or several smaller boxes?
If I do use the amps how/where should I mount them?
If I do use the amps that'll open up another whole can of worms I know nothing about.
I'm sure I'll have more as it progresses.
Any other help will be greatly appreciated. Thanks