I would suggest finding a Tilden safety to replace the one you have. It moves in the forward right direction like current model safeties and not backwards like the prewar wing style. It would be cheaper than finding a bolt shroud. Here is an example of one that sold recently on ebay. You may also try Wisners, they may make a replacement.
The tilden is a conversion of the original safey and it is a 3 position. The part of the safety that goes into the bolt shroud and does the work is identical to the original, the lever is just moved so it operates on the right side.