I never owned a 60's-70's muscle car, but I sure wanted one! The closest I came was a 1969 Bonneville with a 428. I got it for $400 in the late 70's. It had about 60,000 miles on it and some rust on the body.
I had a local vocational school fix the body and repaint it the same color. While they were at it, I had them remove the emblems, nameplates and chrome side dent strips, fill the holes and black-out the grille.
When they were done, I added new shocks (air shocks in the back), tires, brakes and dual exhaust. I also put in a Pioneer rack style stereo system with Visonic David speakers on the package tray.
The car needed leaded premium, but only leader regular was available at the pump. I worked around that by going to a local airport and filling (4) 5-gallons cans with 108 octane purple aviation gas, that I mixed about 40/60 with leaded regular. It was a highway beast! There were no side pillars, so it was completely open front to back with the side windows down.
I loved that car! It was stolen out of parking lot when it was about 10 years old. It was later found stripped and totaled and the thieves were never caught.
I don't think I have a photo of it, but I found this one online. It's close, except for the blacked out grille and de-branding.