My vette came with the original stereo, but i soon swapped it for a more recent one, with a 6 disc changer in the jack storage box. (Kept the old one - its a bit of audio history!) If you can crimp wires together, and use a screw driver, then it should be no problem

Seriously, it's not a big, big job. I had to decide whether i wanted to sacrifice my console - naturally the new stereo wouldn't fit in the old hole, so after taking the console out, i very carefully opened up the hole to the right size with a sharp knife and then a file.
You can then buy one of those universal bezels from the audio shops - they fit in the hole and clamp there with specially shaped bendable tangs. Most stereos will then just slot in and lock in position, and are sold with a special tool to get them out again. Wiring's no problem, specially if your vette's already wired for four speakers. Once you have the console out, which you would have done, to modify the hole, 1/2 hour max with the crimping tool, and you should be sorted. I had to take a feed from my clock wire (orange) to supply the memory on my new stereo, but that's really the only mod from stock.
I've yet to move onto speakers - using the standard ones. The fronts look really easy to replace, just lift the grills and undo some self tappers. You can get some pretty punchy replacements for these sizes - although a speaker's only as good as its mounting area, and i'm not sure how rigid the dash is here. Unless your going for block rocking bass, i don't think that should really matter - any new moderately priced replacement for the front speakers will make the clarity so much better, leave the bass to the back ones!
I've got a pair of new six by nines in the back, but the install is only temporary - so much so i'm ashamed to even tell you how shabby it is! Theres quite a few sites on the web showing designs for enclosures for 6x9's. You can't really rely on the old brackets if you want to put anything half decent in there...
This would probably be the most involved part of the whole job (probably why i haven't finished it yet

) So i recommend you give it a go - theres no back breaking contorsionism in getting under the dash or anything horrible like that...
Good luck!

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Red 1980 350 auto w/ quickshsift
Edelbrock intake / carb
Crane Fireball cam
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