Both the 250 and 300 grain .45 SST's available as muzzle loader components are .452" diameter. As far as I know, the only way to get the 200 grain SST's is loaded in 460 S&W ammo, which would also be .452" diameter.
So the 300 grain might not be the best starting point, but I don't see any reason the 200 grain version wouldn't be just fine and the 250 might not be a bridge too far.
I guess the short answer is "No, nobody here has tried it"...