To separate the idle cam from the choke

Google vernier control cables. It is almost exactly what you describe. Can rotate knob to adjust throttle. The ones i sold in the past had approx 1” diameter knob.used with a bead chain, it wont affect normal operation.

my 68 chevy had a manual choke, pull it out and start it, and then i could keep idle up with choke off. If i wanted fast idle,i could feel the steps in the pedal. Was the only manual choke vehicle that would work like that,most didnt work as well.

all the aftermarket choke kits are junk, especially the cable control.