Yes it can. S&W used to do the conversions in their custom shop a good number of years ago, but I don't have any idea if they still do. I do not know what they were doing, but as I recall, the thumb safety functioned in a manner opposite of a 1911, in that upon presentation you flipped it up to take it off safe, instead of down.
MS
Yep. The safeties of 39’s and 59’s worked opposite a 1911.
If the hammer is cocked and the safety is put in the down/safe position, it will drop and the firing pin will be blocked as well. The way I think of it is, if the safety is pointing in the same direction as the barrel it’s ready to go.
