They are out there pretty much everywhere. Is the car missing it’s engine and trans currently? Like Joe posted as far as bang for the buck vortec heads are hard to beat. The flywheel flange on the crank is different on 86 down vs 87 up motors so what you already have is going to depend. That car should have a TH350 I think. Anyway LS1tech , thirdgen.org and craigslist are all good places to find used parts on the cheap.