I had a last second change of heart. My hand needs rubber between it and steel for the 640 to make sense to carry. So since I have a sudden aversion to alloy frames... The Lady Smith gets a new pair of shoes and a range visit tomorrow:
I did take the sharp edge off with some fine sand paper and the fit is again near perfect. There is a slight amount more gap with this stock since the wood is more rounded. My hand doesn't feel a thing but I will see tomorrow at the range. If this works out well, this may be my carry gun over my 637 if it gets repaired.