Checking for rust … common areas?
Not hard to turn into a 73. Parts will bolt on. Add in a bumper and hood latch support. In fact I think I have all those parts. If you're set on building a 73... most consider the 72 front end to be more attractive. So you're set on a 4 door? The interior may differ some from 73 to 74 as well.
The distance is more reasonable but you must be prepared to walk away if its not as advertised and eat the loss of time and travel expense. It's easy to make an unwise compromise after driving 5 hrs with a trailer. Talk a lot to the owner and get much more specific on dings and rust. Pics never show it all. Be sure to get there in good daylight with a plan for how to look underneath.
Edit: one more thing, kinda funny I think... lotsa guys want to turn 73 up Dusters into 72 down... should not be hard to get rid of the 72 front end.
Here's an example I stumbled upon in new postings:
http://www.forabodiesonly.com/mopar/showthread.php?t=206498