Congrats, Thats a very nice looking 32-20. Wondersight is still in business, the owner manufacturers other items of interest including screw sets for other firearms. I bought one to install on my Brazilian Model of 1917, you simply remove and carefully set aside for posterity the top screw, install the Wondersight base which has a base that allows for elevation adjustment. A tip I received from the manufacturer was to put a piece of black electrical tape cut to the size of the base on the revolver side of the base in order to eliminate any possible scratching of the revolver. Once the base is aligned and in position the provided screw is tightened into the top screw hole. This screw is only loosened for adjustment in elevation. I think they are great and cause no problems associated with alteration of a firearm.