Several years back a customer sent me a 44 that was supposed to be a 25-20 but the brass was opened up and split. I did a chamber cast and found it had been re-chamber to 256 Win Mag. I told the customer that this was way to much pressure on the old gun and he ended up selling me the rifle rather than invest money in a repair. I checked what calibers the 44 was made in and found that the standard action could be had in 38-40 and some with the hammer block were made in 32-40 and 38-55. I made mine in 44-40 just because I had a barrel on hand. The 44-40 and 38-40 are loaded to the same pressure so as long as I don't try to hot rod it there should be no problem. The 44 was also made in the 28-30 Stevens but I could not find any pressure listing.
I have in my collection two breach block that have been broken. One was welded back together but I don't think it ever got used. This was caused by someone who re-chambered a 25-20 to 25-35.

I’d sure like a centerfire block for one of my 44’s.  It’s a .32 Rimfire Long.  I’d like to shoot it with my centerfire .32 Colt Long brass and not have to convert the brass to take rimfire acorn blanks.  I’ve got 10 pieces of converted reloadable rimfire brass, but range sessions aren’t real exciting 10 rounds at a time.

I am considering making a second barrel in .38-55 and setting up a second extractor since I already shoot that caliber.

.38-55 in an original Stevens 44 1/2 can be difficult to load a round into the chamber due to interference with the hammer. You may have to bring the hammer to full cock for the cartridge to clear it.