Thanks, guys--I am encouraged. I have a .410 220 in nice shape and will try to find a ratty .410 barrel to use for the monobloc, then look around for a 'smith willing to do the job. Think I'll go for a .25-35, since I like the chambering and have the dies. If I can't find a .410 barrel to use, I'll look for a 20 or a 16 and find another forend iron for it (even I can make the wood part of the forend, but a .410 220 forend is best because it fits the rifle barrels without any changes).
Remington40X, they came in .30-30 (most common), .22 Hornet (pretty common), and .25-20 and .32-20 (NOT common), plus some other R&D chamberings (damn rare). I've had all of them but the .32-20 and .22 smoothbore.
