Wanted 70-76 duster project

You can easily be under 20k if you don't want a quality paint job. Paint and body work will crush that budget 60% immediately
Problem is your idea of what a quality paint job is likely different from mine and likely different from the OP. And while the OP might have intentions of building a 20 or 30 footer, it’s likely that once he’s into the job, he will want a 10 footer which will jack up the project cost part way through.

Unless it’s a highly sought after A body (ie: original 340 car) and is solid to start with, restoring any type of A body to a decent condition is automatically a money losing project. But if there are no intentions to sell it, then it doesn’t really matter how upside down one is in the build.