I try to avoid the autozones, adavanced auto and other franchises for everything except oil and other "shop expendibles". There are a couple old-time privately owned parts shops here, and if I need something fast, they always seem to have it, and, they know how to look parts up in a book.
Funny story - I needed some chains for my engine lift, so I went to Advanced Auto and told them, I need some chains for my engine lift, you have them as part number ###. Well, the counter person immediately went to the computer and started the "What make/model/year is it?"... <sigh> She had to get a manager to find the chains, which were right behind her on a shelf...
Otherwise, online and catalogues specific to chevy seem to have the best selection and with overnight shipping, or even ground delivery times, it's not that big of a deal to wait.
Ricers are everywhere, muscle cars, rat rods, hot rods race cars are not. Businesses have to provide for the demand or the competition will take them out.