340 magnum from 73 dodge dart rebuild

You've already selected a shop, and they didn't give you a price??
They're going to ask you the same questions that you'll be asked here-
There's cheap parts and there's exotic parts and there's everything in between. What do you want?
What kind of heads are you looking for? Stroker crank? Stock rebuild?
What are you looking to have with the finished engine- strip only, street/strip, cruising to the ice cream parlor, daily driver, etc... there's lots of BIG differences that will be reflected in the cost.
You need to have a heart-to-heart talk with your proposed builder.