Ask about internal parts, what brand and part numbers. You could be getting the cheapest parts made from a decent parts manufacturer. $1790 is about what you would expect for a reman engine, some of the local parts stores may be cheaper, but you will get a cheaper engine.
I live in the KC area, so I might know the builder, do you mind naming them?
The overbore and crank information is good to know. Also check what the warranty covers and how much the shop will cover.
All your 250 parts should interchange, the carb should be swapped to the larger bore but I believe it will still fit the 250 intake. The 292's used a bigger exhaust manifold and pipe diameter, but the 250 stuff will work. Check the starter mounting, some used a three bolt starter, most use two bolt.
Joe