Looking for advice. Want to build a Duster to run on a budget.

I agree. Once again it’s better to do nothing then repair it wrong and cause more damage in the long run and have to redo it. Costing more. So if your argument is cost, then do nothing. It’s the cheapest. I’d rather have a rusty car then a rusty car covered in fiberglass and bondo with a paint job.
That's why I did a good fiberglass job . Bodywork and paint complete and no worries of it receiving any more damage.
A preservation is an alternative to a restoration . This car was more suited for a preservation and that's the route I took.