being so old im sure theres no holes in the doors, but you could cut some.

the rear speakers i always used a speaker boxes for 6x9 speakers, then round sub/amp combo deals fit well too.

then if you really want to spend money you can make or buy a custom speaker box deal for the back wall of the cab.

as far as what radio, that all comes down to do you want to cut the dash up or not. skys the limit on what set up you want. double din can be done easy. its just a power and ground wire to run it, the rest your running all new speaker wires and all for any HU you use.