Well... I guess it would depend on what you're going to do with it... Since the #3 was available in .375 Win... (Basically the same case), I'd think that any #1-B or #1-S could be rebarreled... As they share the same barrel contour as the #3. However, you
MAY be confined to a 22"-24" barrel as the taper
MAY be too thin beyond 24". Personally, I don't view that as a problem... As the 24" length will give you about all the velocity that the case will stand pressure-wise.
Unless, of course, you intend to shoot Black Powder... Then you will likely need 30"-32" to optimize velocity.
If it were me, I'd likely just look around for a #3 in .375 Win. If you really want a .38/55, a gunsmith could lengthen the chamber the amount needed and you could likely shoot both. Of course the Ruger action is much stronger than a lever Marlin or Winchester 94.
I distinctly remember one of the writers stating in print back when the .375 Win. 1st came out that he shot some factory loads (.375 Win.) in a .38/55 with no ill effects. (I believe just some handful of rounds... NOT a steady diet...)
Most of the advantages of the #3 to customize are now negated by their inflated value. i.e: Most #3's now cost as much as a No:1 donor...
I, myself; have #3's converted to .32-40 Win, and .356 Win... and I purchased one in .338/06 AI.
But these were back in the day when #3's were cheap...
Plus, I have a #3 action waiting for inspiration to strike... (I'm thinking .35 Win or .444 Marlin...)
Hope the above commentary is of some use to you...
GH