It's better to have a crumbling rim blow switch than one that's intact and would start the horn honking when the interior temp exceeded 80 degrees F! As the one in my '70 Monaco did. Cooks the horn relays, too!
When I got my '70 Monaco Bro. in '75, the rim blow switch was hard and the horn didn't work. I bought it that way from the dealer (as a used car). We figured he didn't know it had a rim blow wheel, trying to use the crossbar as the horn button (which didn't work that way). I later found the horn relay was cooked internally. A new relay and the horn worked IF I pushed hard enough to make contact in the switch. The service manager related how difficult it was to change the rim blow switches.
IF the relay didn't go, the spring which held the contact for the horn (a part of the turn signal switch) would weaken and the contact wouldn't make the necessary contact with the cancelling cam. So I changed a few turn signal switches! I finally took the cover off of the horn relay so I could use my foot to manually make the horn work.
I've been considering one of the repro Tuff Wheels as a good alternative, somewhat correct and also "period correct".
I think the Rim Blow option was a good idea (as Ford and GM had them too), BUT it obviously wasn't good enough for it to remain an option for more than a few model years.
When I could still get one, I got a new one from Chrysler. Only in Basic Black, though, but with a new switch in it ready to install. Looked like it could have also worked for a Tilt 'n Telescope column than just for a tilt column, with a little grinding.
Y'all might have had better luck with them where you're located, but my experiences were more like an exercise in futility. I imagine that a wheel from a '74-era C-body would look similar and install pretty much as the '70 steering wheel does? Just need to get it "painted to match".
CBODY67