The two most common steering dampeners for these machines were an Indian badged unit using a handlebar nut secured slider plate with a yoke straddling the top fuel tank ears and the Crocker to which you refer which is the best of the two. Have both types on my machines and prefer the Crocker. Got mine completely original in chrome years ago (too expensive) and only replated it because the knob had come adrift and skipped down the road prior to my purchase. It, like all I've seen - except one- was chrome. This unplated one was polished like an old door knob on a crusty old 442 with chair and as he'd copper plated his Indian head tank badges and polished them to match, the dampener finish was suspect.
What varies on the ones you see now is the restored finish done to the brass components before plating. The originals were a tad rough but as brass is very easy to buff, platers often turn these into jewelry to distract the customer from the fact their rims didn't come out nearly as well. As I'm sure you're aware, Michael Breeding reproduces these fine units here
Choke position: 440's were fitted with a one year only DLX 124, last of the Scheblers before the Linkerts commencing with M441 in 1941 and their crude choke handle consists of a short bent plate mounted on the left directly to the choke shaft as you face the machine behind the a/c and have no provisions for cammed low speed needle enrichment. Never seen any extension for this choke arrangement.