Don't mean to sound disrespectful here, but I can't tell you how many times I've read on this forum that somebody was having a hard time finding a part. It wasn't to long ago that someone said something about not being able to find a camshaft thrust plate for a sbm.
for some rare trim bit or super specific one year only doo-dad or whatzit? sure, stuff can be hard to come by. and, yeah a bunch of stuff isn't made because there is no market for it, or it's just not profitable.
but the parts are out there. you just have to have the drive and tenacity to find them and willingness to open your wallet when the time comes.