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

hell my car was $1700 and i was still under 4k getting it running. and in my experience, many car guys out there are really nice and receptive to guys trying to build cars on a budget. every engine I bought the guy selling threw in some sort of discount or extra parts for free or $20 extra without asking. I got a 4bbl intake with my 318 for free, my 360 was supposed to be a short block only for $250 but the guy threw in all the valvetrain and bolts for the engine as well as a transmission for no extra cost. I know mileage may vary, but overall a lot of people are willing to help just out of the kindness of their heart.
Last year I had 2 225 slants left, complete , stand bore, good motors, cheap. I finally finally had a kid and his dad come for one, I gave him the other!! Glad to see it all go to a good home!
Yes bargains can be had, the best approach is travel to see parts, make friends, show a love for building a car! and be NICE!

I will add this. Find the most complete and most straight and most rust free builder you can find and afford, and be in reason for $ spent.

The classic car market is soft, yet so many want way more than a project will sell for. At least around here! Tons of overpriced projects for sale for way more than they will ever bring.