Langdon has the best price for the adapters, and also has a linkage kit that mounts outboard of the carbs, and, if memory serves, requires a cable throttle. I wanted mine inboard with a throttle rod, so I built my own (at significant expense!). My throttle setup won't work on most cars unless you are using a tall manifold like the Edmunds; I would have used the Langdon setup if I had been putting the carbs on my Offenhauser manifold.
The short throw and stiff return springs are not a problem, since you need to increase the ratio to match the throw of our throttle pedal anyway.
The electric chokes require a constant, ignition-switched supply with 14 gauge wire. I used them simply because I didn't see an elegant way to keep the choke butterflys open all of the time. I never had chokes on my dual Stromberg setup, and it started just fine.
Marty