Carburetors equipped for manual choke have different, much longer choke lever arms so you can effectively modulate the choke by means of a sufficiently long travel from open to closed. They often have a poppet valve in the choke plate, a spring-staging setup, or both to allow air to bypass the closed choke plate once the engine starts (the manual-choke equivalent of the choke pull-off) and they have smooth rather than stepped fast-idle cams. I haven't yet seen a manual-choke conversion on an auto-choke carb that really worked well enough not to bug the carp outta me.

The difficulty is the difference between the V8 and \6 choke lever. The \6 choke lever's rod attachment point is spaced further away from the carburetor and is rotated slightly vs. the V8 lever. Late Carter BBDs have the choke lever attached to the end of the choke shaft by a screw, so the V8 and \6 levers can easily be swapped. The Holley lever is swaged onto the end of the shaft; no easy swap. I keep meaning to check and see if the necessary choke shaft and lever assembly can still be had from Holley. Probably not, but I will try to remember and get around to it sooner than later.

In the meantime, I definitely have better results starting with the electric choke kit, making my own choke pushrod from brass rod stock of the correct diameter. I can compensate for the closer-to-carburetor V8 choke lever by making the carb end (top) of the pushrod longer than the original pushrod, then using two circular spring clips to secure the pushrod to the lever (one on each side of the lever). This is often enough to resolve the binding and allow the choke to operate correctly. If not, a bend can be placed in the rod to help make the angles less impossible. Make sure you're using a thick carb base gasket to lift the carb high enough; that in itself can do the trick!