US vs ROW car value
 

If you had the same two examples. Numbers matching 73S from US & another numbers matching imported ROW 73S. Would a ROW car be more or less valuable being a European delivered car?

They were the same in 73

Everything including headlights, turn signals, mechanicals? Anything of note that would set them apart?

Headlights, color of turn signals, were different. As I said in your other thread, check for the carbon filter next to the drivers side battery. Your car has the rubber bumper extenders so that was for the US market.
Mechanically no differences, but the car you are looking at has been very nicely modified with Euro parts.(like the 2.7RS engine conversion).

I would buy the one you like most.