Yes you're right. I wasn't very clear, I meant the dovetail should BE deeper, not to cut it deeper. Like you say it will now be too wide if cut deeper. A guy could use as is though, now I think about it, by putting a set screw under it like the alloy frames.
I shoot shortened versions of both the 218 Bee and 32-20 in single six 32 frames. They're kind of wildcats but simple to reload because no wildcat dies are needed. Standard dies work fine. Some brands may need the seating die body shortened a bit but that's a simple matter.
And that was my intent. Add additional center fire calibers to the single six w/o requiring special dies, custom barrels or lengthened frames. Just re-chambered cylinders.