OK - so where have you seen or heard that such an animal exists? Outside of a possible velocity gain I'd see no benefit unless you're expecting less muzzle rise from the extra weight.
I suspect by the era of the model 52 that Olympic centerfire pistol competition was taken over by the .32 Long wadcutter.
I also vote model 41, perhaps the -1 in .22 short, although I have not heard of a specific barrel for these used in world competition. A .38 bullseye gun with a 2" longer custom barrel would have stood out. A lot.
Tool room or experimental examples that basically never left the company have been made in various different models over the life of S&W, and probably still going on. You have to build prototypes to figure out what you may want to put into production. Not much would surprise me.
How many have ever seen the Olympic rapid fire prototype S&W made?
Far as I know only one was ever made and current location unknown.
I remember many years ago there was a model 52 for sale on GB and it had a matching 9mm top end . I think there was some documentation with it. Dont think it was outragous of course 10-12 years ago nothing was.
I picked up some really odd stuff from the estate of past S&W engineer. The long 52 barrel....
A 38 AMU model 39 barrel.....
And what appears to be a Model 39 barrel in .380 and a second one .22!!
I'll post some pictures when I get a chance...........