66 C20, $300 budget ideas

[earl84]

I am not knowledgeable on stereo systems at all. I have done some looking around in this section and other sites, but would love some recommendations. Some with exact model numbers would be great. If you have time to help it would be great, if not I'll eventually figure it out on my own.
My truck has PO holes in the door that need to be filled with speakers, a PO cut dash that needs to be filled with a head unit, and the original dash speaker location with nothing there. A head unit with USB port for plugging in a thumb drive would be great. Don't want to run anything hidden to the glovebox. My truck is not super original looking, which I love, but I made concessions in my seat and a tilt wheel and it had a sunroof already installed (I hate it), so a modern head unit is OK.
I like classic rock, some country, and a lot of music like imagine Dragons and Amos Lee (who I saw at Red Rocks last week, amazing!). Don't need it cranked up super loud, don't need heavy bass, but I am willing to spend some money to have nice crisp, clear, full sound. I'd like to keep it around $300, but if that's not reasonable to get crisp, clear sound at reasonable volumes, I can easily go higher, but not more than $500 all in.
I have a new wiring harness installed, so my wiring should be able to handle whatever.
Thanks in advance for your help.