Hello,
If I'm reading the Smith Bible by Supica and Nahas correctly it should start at around $1250 and go up for the condition you describe. But that was a couple of years ago and doesn't include the box which is worth several hundred. One thing to look for is the fit of the grips on the bottem of the frame. At serial # 72000 it is most likely a long frame and the long frame magnas are very hard to come by I'm told.
Sounds like a very nice gun to have. Good luck.
Mark

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Mark Connot