Thanks to your help I was able to figure out what kind of sight I needed.  What's more, I was lucky to find one.  Egads was it expensive!  But, such is life - press on or give up.   ;) 

Here are some pics.  Someone varnished the wood way back in time and everywhere it's been dinged or scuffed it's picked up dirt and oil, so that's not optimal but the good news is it's all numbers matching, no import marks, and the bore is perfect - glassy and sharp.  I look forward to getting it out on the range.

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