The Hoosier Sub Carburetor leans the mixture by adding heated air, increasing flow as the throttle is opened. These are hard to find WITH the original heat stove. Asking $95 plus postage.
Here's some literature that is digital only and can be copied to go with the unit.
As an aside, The advertised price of $10 in 1920 is equal to $130.44 in 208 dollars!
Emails only please.