Okay, for what it's worth I did a little experimenting today with my S&W M27-2 with a 6" barrel (no pic, but everyone knows what an M27 looks like), and my recently acquired Rossi R92 with 24" barrel. (The R92 is a clone of the Winchester Model 1892. I replaced the safety that Rossi puts on the bolt with a peep sight.)
I was able to chamber, fire and eject .38 Super ammo out of my M27, PMC 115gr JHP. It says it's +P on the box. Accuracy was fine and average velocity for 3 shots was 1164fps.
The same ammo would not cycle through the Rossi R92, the cartridges would never operate through the mechanism. But I could single load it into the chamber, fire and eject without any problem. For some reason I could never get it to register on my LabRadar chronograph so I don't have any idea what the velocity might have been.
For comparison, here are some average velocities (for 3 shots) that I got out of the S&W and the Rossi with some of my handloads:
.38 Special 125gr JHP with 8.2gr Blue Dot
M27-2: 943 fps
R92: 1328 fps
.357 125gr JHP with 20.0 H110
M27-2: 1281 fps
R92: 2161 fps
.357 158 plated HP with 15.0 2400
M27-2: 1169 fps
R92: 1862 fps
I don't know what might be required to make a .357 1892 style action work with the short cartridge length of the .38 Super, but it doesn't look like any rechambering would need to be done. And if the velocity increase that we see with the .38 Special and .357 holds true for the Super, we might expect to see 1500 fps or more (from a 24" barrel).